text:
Is my phone encrypted with my password?
I have a Galaxy S5 running LineageOS 14.1.
The device settings state that the device is encrypted.
I set up a password, and select to require password at boot.
I then set up a PIN for unlocking the screen, but did not select to require PIN at boot.
When I boot the phone, it does not ask for the password to boot and only the PIN is required for unlocking the screen.
Is my phone encrypted with my password?

Have you taken look at the Logcat? It sounds like encryption is not working.. However, if the pin is asked for before even the lock screen appears then yes it is encrypted.

How do I use logcat to determine that encryption is working?

Is your recovery TWRP? If it is, you could boot into it and see whether it asks for any kind of password in order to mount /data. If it does ask, or if it has problems while trying to mount /data, then encryption is working just fine.

@Paul, did you try to follow Ka1S3 answer?

@Suncatcher Yes, although I don't recall all of details, but the answer is no longer applicable due to a change in AOSP. However, what I described in my question is a condition where there is some sort of default password for unlocking encrypted AOSP. This default password is actually known by the TWRP project, because TWRP will automatically attempt to use the default password to unlock. However, if I select to encrypt with the PIN, theoretically the PIN is uniquely useful to decrypt on each phone. Thus, the PIN is very secure, with the exception of an over-the-shoulder attack.

You device is encrypted, but PIN is used for unlocking master key.
From
I set up a password, and select to require password at boot. I then set up a PIN for unlocking the screen, but did not select to require PIN at boot.
we can assume that you wanted different lock screen && encryption passwords.
Because you are using LineageOS, acquiring root for ADB is not issue.
For achieving what you presumably intended 1st define lock screen password or PIN - select Require password/PIN to start device. Lock device && do a power cycle - not every1 will agree with this procedure, but I tend to verify.
After successful bootstrap, for different encryption password you should either change password via ADB or terminal or purpose built application -
SnooperStopper or Cryptfs password manager
If you preffer ADB or terminal, while in shell, issue
adb root && sleep 2 && adb shell "vdc cryptfs changepw password [curent PIN/password] [new password]"
and hit return; if terminal is only option for you, issue only vdc cryptfs changepw password [curent PIN/password] [new password]
You should always verify PW with
vdc cryptfs verifypw [PIN/password]


text:
Cannot send/receive MMS on Project Fi with unlocked Blu Advance A6
I have been trying to get my unlocked Blu Advance A6 on Android 7.0 working with Project Fi and I can't seem to get MMS messages working in the default app or Signal.
Regular text messages can be sent and received OK, but when an MMS comes in it just says "Tap to download" and when I try to send one it says "Not sent. Tap to try again."
I thought that maybe it was due to the APN settings being incorrect but the Access point names menu that is supposed to be located in Settings -> Wireless & Networks -> More -> Cellular networks is missing. There is only a toggle for Data roaming and no other items.

Well it appears that installing Google Hangouts makes messaging work. Although the app is pretty slow.
For the APN settings, the Project Fi app disables that menu when it's installed according to this:
https://productforums.google.com/forum/#!topic/nexus/F9TYPTE11to
According to that post, you can run this from an adb shell to re-enable it:
settings put global hide_carrier_network_settings 0

source: Stack Exchange

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/3.0/

sort: votes


text:
How to restore my phone, after replacing my systemui with a modded one?
I recently saw a thread about a modded systemui on XDA here and downloaded it. I replaced my present systemui with this  one and rebooted my phone. I think that at first the replaced systemui didn't work so I got a systemui-less experience  (You can learn about my experience by reading the comment I made on SO here ).
Then I learnt that I hadn't set the permissions rightly so I changed the permissions of the new systemui to 644 as said at XDA and rebooted my phone.
After the reboot my apps were optimized as it happens after an update. But this time the new systemui worked  (probably) as I now have an all black screen after my phone boots normally.
I then tried to enter into recovery mode and wiped the data (factory reset option) and booted again, but that was of no use as the problem persisted.
What can I do now?  Will I have to go all the way reflashing my phone? Could anyone suggest a better option as reflashing seems to be the last option for me. Thanks in advance.
Phone model: Lenovo Vibe C, 16 GB variant, currently running Android Lollipop.
EDIT

It was all my fault as the mods were meant for Samsung galaxy alpha (I did not read the title at XDA before messing up)
I don't have a custom recovery installed nor do I have a NANDROID backup made before. I'm completely helpless.

You've learned it the hard way then: Before tampering with system files, always make a backup – especially from files you replace. With some luck you can find someone using the same device and Android version you're running, who can give you a copy of the files you've replaced. But Android.SE is not the place to ask for "an app, device, ROM, accessory or off-site resource" (quote from closure reasons).

But even if I get the systemui, how I'm going to place it back. As I've said that I'm now stuck at a black screen. I'm not asking for the file but want to know how to place it back to restore my device without having to reflash it.

Ah. Best option would be using TWRP, which even has an integrated file manager. But if you hadn't yet unlocked your bootloader, that would mean a factory-reset – in which case you're better of doing a "dirty flash" of your ROM (provided you're flashing the very same you're using now, that shouldn't be an issue). If you had USB debugging enabled, you could also place the file using ADB.

If you succeed, be welcome to answer your own question :)

Your best bet would be downloading your stock ROM from online, take the SystemUI.apk and put it back where it should be.

How can I put it back there without a reflash? Can you guide me? Is there any other way in which I can access my system files without having to boot into my os and place the files, as when I boot into the os all I see is a black screen.

all_licenses: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/3.0/


text:
Is Google Play Service a kind of "bypass" of my apps authorizations?
The google-play-services tag info says that it's "A library used by Google apps and many third-party apps to provide location and social functionality".
Does this mean that if I refuse to provide the location to an app, the said app can still retrieve my location through Google Play Services?

To my understanding, there are 2 way to retrieve the current location from an Android developer's perspective:

The Android framework location API: android.location
This is "the old way" and developers are encouraged to adapt the newer API:
The Google Play services location API.

To access the former, an application has to request permissions to use them:

Unless noted, all Location API methods require the ACCESS_COARSE_LOCATION or ACCESS_FINE_LOCATION permissions.

To access the latter, developers still have to request the same permissions:

Apps that use location services must request location permissions. Android offers two location permissions: ACCESS_COARSE_LOCATION and ACCESS_FINE_LOCATION. The permission you choose determines the accuracy of the location returned by the API. If you specify ACCESS_COARSE_LOCATION, the API returns a location with an accuracy approximately equivalent to a city block.

So, no, the service does not offer a way to bypass permission checks. Both ways require the same permissions.

No, the service/libraries still require permissions requests just like everything else.
See the Play Services SDK documentation for more info. But some relevant excerpts:

...Once you’ve declared the APIs that you want to use ... ensure that you have the required permission before calling an API.
...
If the call returns false this means the permissions aren’t granted
  and you should use requestPermissions to request them.
... when you call connect(), Google Play services validates that it has all the necessary permissions needed. ... connect() fails when any permission groups needed by Google Play services itself are missing.

Well, you kind of confirm my fears... If I refuse a permission to an app, but Google Play Services has it, your quotes kind of say they act independently and therefore the bypass actually exists. If not, would you clarify how? Thank you anyways for taking the time to look this up in the SDK documentation.

As far as I can tell, it is still per app. The request permission call comes from the app, as the library to call out to Play Services is still within the app context. Though I haven't confirmed this with testing yet... I could be interpreting the docs wrong?


text:
Get GPS coordinates of lost phone even if GPS was off when lost
I usually turn off my GPS to save batery. However, I would like to be able to turn the GPS on remotely and get its coordinates (e.g. by e-mail). Today a friend of mine almost lost her phone on the forest... In case next time it were my phone, I would like to be able to locate it easily.
I tried Android Device Manager as mentioned here but it gives me the coordinates of the last time I had my GPS on and it does NOT turn the GPS on to give me the latest/current coordinates.

If you use well-written applications, having location services enabled will not mean that they will drain your battery. These features should only drain your battery if you are actively using them.

Fair point @mattm but do you know how could I check which applications are draining my battery with improper use of GPS?
Aditionally, there is the privacy concern of having every single trip tracked.

I happened to have a Samsung phone, so you can use the FindMyMobile service, which can get you the coordinates of your phone even if your GPS was off when you lost it. However, you need to register in the web beforehand and authorize the Remote Controls in the menu Settings/Lock Screen and Security/Find My Mobile/[Log in with your Samsung details] and then activate Remote Controls.
It would be good to know any alternative for those not having a Samsung though...

This does not answer the main question, but addresses the side conversation in comments about why battery life should not be a significant concern to leaving location enabled for lost phone situations.
If you use well-written applications, having location services enabled will not mean that they will drain your battery. These features should only drain your battery if you are actively using them.
You can see which applications are using location services under Settings->Security and Location->Location (exact menu varies by version). This screenshot is from Android 8, but I think this feature is present at least from Android 6.


text:
"Verification failed" upon startup after installing software update
My phone installed a software update and upon restarting, I get a 'verification failed' error message. It continues "Unable to restart you device. The integrity  verification has failed. You need to reset your device to factory default settings. This will erase all your data."
The only option it gives is to 'reset device' - I do not want to do this and lose all my data!
I tried powering off and restarting in safe mode, but to no avail. How can the update be so flakey!? At the expense of all my data...?
I loaded the recovery screen and wiped the cache. But still no result.
Thank you in advance.


text:
Script to pull from directory containing spaces
I'm trying to pull Whatsup images from my android phone via ADB using the following script:
HOST_DIR=/myImageDirectory
DEVICE_DIR="/sdcard/WhatsApp/Media/WhatsApp\ Images"
echo started
for file in $(./adb shell ls $DEVICE_DIR)
do
    file=$(echo -e $file | tr -d "\r\n"); # EOL fix
echo $file
    ./adb pull $DEVICE_DIR/$file $HOST_DIR/;
done

The space in the source directory is escaped successfully for ls but not for pull. That is, i get the list of files but cannot pull them.
Here are 3 lines of the output:
IMG-20171101-WA0003.jpg
adb: error: remote object '/sdcard/WhatsApp/Media/WhatsApp\' does not exist
adb: error: remote object 'Images/IMG-20171101-WA0003.jpg' does not exist

What gives?

Get doublequotes:
for file in $(./adb shell ls \""$DEVICE_DIR"\")
                               ^           ^

./adb pull "$DEVICE_DIR/$file" $HOST_DIR/;
           ^                 ^

And remove backslash escapes:
DEVICE_DIR="/sdcard/WhatsApp/Media/WhatsApp Images"
                                           ^

Thanks, that did the trick! I now get a different error: adb: error: remote object '/... /WhatsApp\ Images/IMG-20171031-WA0000.jpg' does not exist. But i can pull one file at the time, it clearly does exist.

@Ivana Updated. Remove backslash escapes as it's counter-productive in quoted strings.

@iBug I usually set `IFS=$'\n' before playing with spaces, as to avoid headaches. You may want to add this in your answer.

@DeathMaskSalesman But I myself ain't very familiar with IFS...

@iBug As I trust you're aware, IFS specifies what character the shell interprets as separator. The default character is a blank, which makes the shell choppy when having blanks within paths. IFS='\n' tells the shell to treat a newline as the separator, so that one can safely meddle with the abovementioned kind of paths.

The answer by iBug solves the first problem but creates another. The trick is to leave out the quotes around the directory name, and only add them around the directory variable, like this:
HOST_DIR=/myImageDirectory
DEVICE_DIR="/sdcard/WhatsApp/Media/WhatsApp\ Images"
DEVICE_DIR_noescape=/sdcard/WhatsApp/Media/WhatsApp\ Images
echo started
for file in $(./adb shell ls $DEVICE_DIR)
do
    file=$(echo -e $file | tr -d "\r\n"); # EOL fix
    echo $file
    ./adb pull "$DEVICE_DIR_noescape/$file" $HOST_DIR/;
done

And i yes need to clean up the code, but this works.

iBug has already updated his answer – yours now causes some confusion, especially as you're mixing quoting and escaping. As you basically want to say the same: wouldn't you agree iBug's answer suffices?

for ADB (not shell) command before and after SPACE input "
example adb pull /sdcard/Wi-Fi" "Direct /C:/1/
result files from "Wi-fi Direct" folder copied to folder 1 in C hard drive

all_licenses: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/


text:
'Charge This Phone' vs 'Charge Connected Device'
When connecting my phone to my laptop, I have these two options

Charge this phone (Just charge this phone)
Charge connected device (Charge the connected device via USB)

I don't understand the difference between these two options.  However, if I try the second option, it fails with the error

Unable to use USB cable for Charge connected device

To the best of my knowledge, the ports I tried were USB3, so that nixed my guess as to what the problem was.  What is the difference between these two options and if the latter is better, how can I use it?

Charge this phone

It means that your phone will be charged from the laptop battery via USB.

Charge connected device (Charge the connected device via USB)

It means to charge your laptop via USB from your phone. Most probably, your laptop (like that of many others), cannot be charged via USB, so if you choose that, it is giving an error. But the option still persists simply because your laptop runs on battery. Had you connected your phone to a PC, this option would not have come.

While laptop is certainly a weird choice to charge, I have a feeling the second option is possible to be used to charge USB OTG devices.


text:
Turn off search history on Chrome?
If I search for for example "lemon" in the address bar in Chrome on Android, days later if I start typing "L" it will show "lemon" in bold text as a suggestion.
I have already gone to the Activity Controls and turned off everything there except "Device information".
I simply can not find anything to turn off this behaviour, but surely there's got to be a setting for it??

The setting might be for future prediction. In your case you have to delete from history. So maybe clear the data.
Or more specifically as you asked for chrome Android, long press on the prediction and a pop-up will come stating "Remove suggestion from history?". Tap yes.

Thanks, but I don't want to have to manually delete every suggestion. I want to disable them completely.

You can clear your history on close for Chrome. "Remember history until I close..." or something to that affect.

Not really. Chrome is designed that way. The easiest way to avoid these is to always use Incognito mode so that it does not keep any history but you cannot do things like opening previously closed tabs either since nothing is kept. On most Android, if you leave Chrome in an Incognito tab, it stays that way until you open a regular one, so it not time consuming to simply stay Incognito.


text:
How to reset location_provider_allowed
as the first, my environment:
Samsung S7, LineageOS 14.1, which is Android 7.2.1.
I'm using tasker to set GPS On and Off in this way:
GPS On:
settings put secure location_providers_allowed +gps,network,wifi

GPS Off:
settings put secure location_providers_allowed -gps,network,wifi

Both script are running as root.
Somethink happend (maybe during I tested this scripts) and now I can't switch my GPS Off (in Settings menu), and when I list my settings in this way:
settings list secure

I can see this:
  location_providers_allowed=wifi,wifi,+network,+wifi,+network,+wifi,+network,...+wifi,network,network

It is very long line with cyclic contents.
Please, is there a way to reset this setting (perhaps another than factory reset of phone)?
Thanks in advance.

You should be able to change it to blank by executing
settings put secure location_providers_allowed ' '

If that doesn't work, directly modify the file settings_secure.xml located at /data/system/users/0/. Look for the line containing location_providers_allowed and edit the value for it.


text:
whatsapp issues
I was on WhatsApp for quite some time two years back, and then unistalled it. Suddenly today my friend got a ping that "abhilash left". If Iam using and leave it, the message was understood. If I was using and someone removes me, the message would be "user removed". Please reply as to how it can happen.
(Abhilash)

Whatever be the case, please don't put your phone number here. This is a public site. We should not be held responsible later for any spam calls/messages to your number.

Also, I couldn't understand your problem. We're you in a group that you left, which is why that message came up? Moreover, you can easily contact whatsapp authorities for better info.

I was never in that group. This group was created less than 2 years back and I uninstalled Whats App much earlier to it. How do I contact WhatsApp authorities, s when I wrote to support @whatsapp.com, a message came......google play store is responsible for it which is now not responding in the help forum.

Go to the feedback section in the app.

Did you change your number since you left WhatsApp, or do you still use the same number for regular phone calls ect..?

I installed whatsapp on a single number and never changed it. This was done two years back

If You were never part of the group in which it said that you left, my only guess would be that your friend saved someone number under your name. Let him search your name in his WhatsApp and see if anything comes up.

They couldnt find me on whatsapp? So now what to do to confirm how they got "left" message

It's possible that WhatsApp deletes an account after 2 years of inactivity, Even though i couldn't find any proof for that it's still possible. Now, when you uninstalled WhatsApp you didn't delete the account, so there was still a possibility of you being added to a group. Now that WhatsApp deleted your account it will say in all groups you were in that you left.

Yes, Iam using same number for calls

It looks like someone else is using WhatsApp with the number you had 2 years ago, which is very common.
More than likely the other person using WhatsApp, was added to that group you (your friends probably thought that it’s your number and added it) and the notification occurred becuase the other person left that group.
Now the notification said Abhilash left the group becuase your friend saved your number in his contacts.
Unfortunately you cannot do anything to control this.
that you never part of. with your old number most likely led the group, becuase they identified it as spam, hence them leaving the group caused

Iam sorry to say Mark, Iam still using this number but no whatsapp on my mobile


text:
How to remove pattern lock without data loss?
I have intex aqua super mobile with android 5.1 os.
I aslo try google recovery find my device method but that not working.
How to recover pattern lock without data loss?
Device is not rooted.
Developer mode is disabled.

Have you already checked with our locked-out tag-wiki? If not, please do so. The first question linked there has a full list of approaches. If nothing of that helped, we will need more details – eg. is the device rooted, is USB debugging enabled, what have you already tried and where did you get stuck.

@Izzy i already check this. But I unable to resolve that issue. Because in my phone only pattern lock is enabled and other password i.e. Pin password is disabled. Also Google's email recovery find my phone also not working. I also try to recover my password by locking it by find my phone google recovery but there is no option for forgot password menu.

The entire question I've mentioned is about "plain pattern lock", and there are several additional approaches mentioned – but AFAIR they require at least one of root or USB debugging (or both) being available. I assume you haven't unlocked your bootloader? If you have, there would be a chance via booting a custom recovery from an image (or flashing it).

@Izzy hu how to create image of my phone is there DD command is useful n or not? Also when I connect mobile to computer USB data share also disabled. And USB only function as charger. I think After creating image flashing is harmless...? How to create image of android phone in my laptop Ubuntu 16.04 os installed.

Yes, dd would be the tool of your choice for creeating images of your device's partitions. Trouble is, how will you run it? I could recommend you a tool creating the appropriate scripts which you then just would need to run – but with USB debugging disabled, that wouldn't work. I assume you've neither unlocked your bootloader, so booting a custom recovery isn't an option either.


text:
Does turning "Background Data" off for an app apply to music?
I'm trying to limit the chance of me accidentally using mobile data when I don't want to, and one of my techniques was going to be turning off the "Background data" option for most of my third party apps by individually toggling the setting under System > Apps & notifications > {app}. However, while testing this toggle, I noticed that it appeared as if Spotify was still downloading and playing music while my screen was off.
At first I thought maybe it was playing some cached music, so I decided to force stop the app to clear all memory usage, turn off my cell data and wifi, record the amount of background data the OS claimed it had currently used (25.00 MB), attempt to launch the app an play a song, background the app (bring up the home screen), and hit play on my headphones.
As I expected, Spotify didn't play anything when I relaunched the app w/o any radios on, but when I backgrounded the app and turned mobile data back on, it started playing music.
To make sure I wasn't being tricked by cache again, I checked what the OS recorded for background data and it said 25.92 MB (or, more than before I started - 25.00 MB).
I don't think I've conducted this experiment incorrectly, so is my understanding of the "Background Data" toggle incorrect, does this not apply to music (and third party streaming apps such as Spotify), or is there perhaps something wonky with my mobile device?

IIRC, the "background data" setting is not enforced – it's just a hint the app should (not must) honor. Unless I confuse something, that is.


text:
How can I use Bluetooth and wired earphones at the same time?
I have a Bluetooth earphone and a wired earphone. I want to use them simultaneously.
Is there an app for that? If not, what can I do about it?

Old, but I am interested in knowing why.  Often that helps in people come up with solutions

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/


text:
Sony Xperia Z3 - Lollipop - Signal bar disappeared, no SIM would work
I'm experiencing problems with my 2 yo Sony Xperia Z3. Today i've changed the SIM card from polish T-Mobile to Orange (I've been using Orange for alot of time, even this particular SIM, and 1 month ago have unlocked the network to use T-mobile) and now it seems like none of the cards would work.
After turning the mobile on there's no SIM pin typebox and the network stays at NO SIGNAL (grey bars with an X on them)
What I've tried:
- rebooting (changes nothing at all),
- different SIM card (still this same happens),
- turning plane mode on (would make the signal bar disappear totally after trying to turn it off)
Any clues?

When you try making a call, does it try, or does it just say emergency calls only?

@Abochur actually i found out that my IMEI is wiped (empty space where it's supposed to be after *#06#), guess my baseband/modem is gone, probably wouldn't manage to make it work as i have not made any TWRP backups of system

Try flashing firmware, this should fix the IMEI. If not, you'll need special tools to repair the IMEI.


text:
How to fix in-app (google) maps after Google Play services update broke map functionality?
I am running AOS 6.0.1 (API-23) on a non-rooted phone. It's been working perfectly for months, but one day after updating some apps like Uber, Viber or Windy, I was told that Google Play services need to be updated as well and would not work properly, until then.
I then updated Google Play, Google Play services and Android System WebView, but then none of their maps was working, meaning that maps based on Google maps are just showing an empty blank map canvas without any features except the pins. I.e. showing the cars in Uber but no background map.
Somehow, after having installed all and everything Google related for my device, the in-app-maps was working again. Unfortunately, I have no recollection or idea what I did at the time that made it work.
Unfortunately now, 6 months later, I have the same problem again after some updates but this time I can't get my maps back. Although Googles own Google Maps, always seem to work... Nowadays I always use apkmirror to download, since they show the relevant app variations and are simply better that Google Play Store, which I no longer use. Here for example, is what's shown for Google Play services:

My device is a "440", at least according to the original firmware versions.

What Google related apps are responsible for showing the in-app-maps correctly?
On what do they depend? (I.e. How are they related?)

People on other devices seem to have a similar problem

Most surprisingly, after reverting and/or updating some of the relevant Google apps, some settings got restored to some previous values. Those may also include permission settings and in my case, the Data Usage settings.
I solved this by first ensuring that the following 2 system apps were up-to-date:

Google Services Framework *
(com.google.android.gsf)
Google Play services (com.google.android.gms)

Note that GSF is normally never updated and remains fixed for your AOS API version.
Next, I went to check the permissions of those apps. That's when I found that Mobile data had been mysteriously disabled under data usage. Check by navigating to:
Settings > Apps > Google Services Framework > Data usage > Mobile data: "allowed"
Check both Mobile data and Wi-Fi tabs, and for both apps above. That fixed it!
For completeness, also check:
Settings > Data traffic management > Networked apps and check that data is available on both the tabs Installed apps and System apps.

But since you're on it, you might as well also update:

Android System WebView (com.google.android.webview)
Google Play Store (com.android.vending)

If you still have map problems after this, then (a) make sure you're using compatible binaries (APK) for your specific device (API, DPI, arm version etc) and (b) that the permissions for all of these apps are as allowing as possible. Also, the device clock need to be correct...

You need to clear the ca cache by going to
Settings > Apps > Google Services Framework > Storage > Clear Cache
and
Settings > Apps > Google Services Framework > Storage > Manage Space -> Delete All Data
I followed this video https://youtu.be/gBc5eIPOKWQ
Solution worked for me in Oreo version. Please node naming convention and path to reach cache could be different in different OS versions. But basics are same.
Best of luck.

If you use an Android system review and the device has a slow internet connection, it is very common that when you install an application on the device, the application will not update itself and instead the Android system review will show the version number of the downloaded application. This problem can be fixed by downloading the latest Google Play Store app to the device and then you can then update the application.


text:
I dont know if my tablet is broken or outdated
Well, I have a Samsung galaxy tab 4 (4.4.2) and I rooted it. So I reset it because Google play didn't work.but after factory reset it still didn't work. I uninstalled updates cleared cache, and I tried to system update today, and that didnt work. So I'm trying to find a way to get my system updates working, and Google play working.
HELP

re-flash stock rom again, it will unroot completely.

Possible duplicate of Samsung Galaxy Tab 4 not getting 5.0.2 update

OTA system updates won't work if you've modified the system image in any way, including by rooting. To get back to a working state, you need to flash the "stock" ROM, i.e. an unmodified official ROM from Samsung. See Where can I find stock or custom ROMs for my Android device? for details of how to find a stock ROM, and then this existing answer describes in detail how to use Odin to install a ROM on the Galaxy Tab 4.


text:
Removed Google Apps system app, now the device wouldn't boot
I have a Micromax Canvas A1 device (Android one). It's been rooted and I have removed some system apps on it before. When I disabled Google App, a lot of space was freed and the system worked fine. So I thought I could free some more space by uninstalling the app without any harm. But when I uninstalled it, the 'searchbox stopped working' message came up. I powered off and then on again, but the boot doesn't complete. The android boot animation keeps running endlessly. Tried entering recovery mode, couldn't. Micromax logo is all it shows. Tried the same with adb, it says 'insufficient permissions for device'.
How do I fix this?

Can you list apps that you removed ..and yess reflash your device with stock rom

Removal of Google Apps application caused the problem. Yes, I have flashed stock ROM. It works now.

Reflash the Android One OS by booting into recovery.
First get into the bootloader:
1) Power off your device and wait 4-5 seconds after lights go off.
2) Press and hold Power + Volume Up button together for a few seconds and then release the buttons as soon as you see the boot menu screen
3) Boot into recovery. Flash the Original ROM using TWRP or stock recovery


text:
Execute fastboot commands without PC
I have setup adb server and client within the Android device and can issue adb commands via terminal emulator.
But I need to have the fastboot in the same way. My requirement is to temporarily boot into TWRP without a PC or another Android device:
# fastboot boot /path/to/twrp.img

I think the Android has fastboot-over-usb.

You can't execute fastboot commanda without a physical connection to the phone.
Fastboot is another name for "bootloader mode", where the bootloader stops itself before further loading the OS, and waits for fastboot commands.
Since bootloader is very simple, your only bet would be connecting your phone to a computer.

Does the fastboot-over-usb means the fastboot still can be accessed after booting into Android?

@Seff I'm afraid no. After booting into Android, there's no more "fastboot" mode.

Fastboot is only active while in bootloader mode. Think of the bootloader like a "GUI-less boot menu": device enters bootloader, bootloader decides how to continue by indicators given such as hotkeys hold (boot to recovery?) or specific flags existing (not sure which, but that's what must be the case when eg. having run adb reboot bootloader). Once that decision has been made, bootloader hands over the process to the next instance and exits. See Can somebody explain the boot process of an Android device? (step 2 in my answer there) for details.


text:
Why is the audio category of my files incomplete?
I have recorded some .wav files with my Samsung S7. They are located in a folder of the recoding app.
Unfortunately the audio category of the my files (Samsung) file manager only lists some of them. Those recorded within the last 5 days are missing.
Why and how can I fix this?

What app is it? Its not helpful if we dont know, it could be app-specific.

And by "audio category" you mean inside that app, or somewhere (where?) else?

The app is Zoiper IAX SIP VOIP Softphone Lite, but I think it is a generic problem independent of the recording app. I have also added a link to the Samsung file manager.


text:
Does the carrier matter when flashing custom roms?
I am getting the lg g6 tomorrow and i saw that there was twrp and lineage and a couple others. But xda also has a thread that is specifically tmobile and thats where im getting my phone. but the tmobile thread had 0 developement going on. So will the carrier matter?

Go get the US open variant - only that and the European variants are officially bootloader unlocked at the moment (AFAIK) and thus only them get any sort of development.

Im getting it free so i dont really get to pick.

Also getting the kernel sources you could build your own bootloader and flash it yes? If I remember correctly manufacturers are required to release kernel sources.

Kernel ≠ bootloader. Without an unlocked bootloader you aren't supposed to flash any 3rd-party stuff.

So bottom line if i install the special twrp will i be able to flash lineage

The bottom line to that is you buy the variants with unlocked bootloaders so you'll be able to install TWRP in the first place.

I ended up getting the j3 anyway

Yes and no. Most times probably not, but there are some carriers which not only apply software modifications but also obtain specific hardware configurations from manufacturers (AFAIK Verizon is one of those having done that in the past for some devices at least, and T-Mobile was mentioned in that context as well).
Which means, there's no "generic answer" to this question, but you must check for each device separately. If the hardware matches, the carrier should be irrelevant concerning the custom ROM – as the latter then again matches the hardware.

Andy Yan is right. The phones sold by all major carriers have their bootloader locked. Your G6 variant won't be the same G6 that allows TWRP (and thus custom roms, and root) to be installed easily.
See Post:
https://forum.xda-developers.com/lg-g6/development/recovery-twrp-lg-g6-us997-unofficial-t3629883
Saying :
A message to those with other variants of the G6:
The H870 International variant and the us997 are the only ones with an official bootloader unlock from LG.

Additional info: not even the TW/HK H870DS and the Australian H870 are included - only Europeans get the privilege.


text:
I cannot root or access developer options
My Samsung Galaxy Tab A (model number SM-P550 if you want to know the specs, Android version 6.0.1) will not allow me to "unhide" or "unlock" my developer options no matter how many times i tap the build number. On another note i am unable to root my device and because i do not currently own a pc and i have tried every mobile rooting technique i could find, thank you for adressing this issue.
Edit - so i finnally figured it out, this device has many "accounts" and you can only access thing like the dev options on the "owner" but i was using "guest" but i still cannot root but im sure i will figure it out eventually, thank all of you for your suggestions and help!

What does "will not allow me to access" mean? What did you try, and what happened?

Did you try tapping on the build number 10 times in the "About Device" section? That enables the developer options.

What i mean by access is no matter how many times i tap the build number and no matter what else i do i cannot "unlock" or "access" the developer options.

Look like you're running a quite old AOS version (6.0.1) from early 2016, and unfortunately Samsung are notorious for buggy firmwares. I'd recommend you to look for a different updated firmware and try that. Or if recently bought, take it back to your shop. As WillW said, all shop bought Androids should have this possibility, unless you got a stolen device that have been blocked somehow.

Could you [edit] your post to include all the relevant information? If people have to watch a video to understand what your problem is, they're much less likely to try to help. It also makes it less likely that your question will come up in search results.

@not2qubit no infact its roughly 6 months old so i cannot take it back to the store where i bought it, also i dont even remember where that is. But i think this firmare idea sounds pretty good but i dont know how to do that.

@Gokul NC - im sorry i dont understand whet you mean.

Every Android should be able to get developer options.  Wrichik Basu's comment says how to show developer options. However OEM Unlocking (first step to root) is disabled on basically all Samsung phones.

Yes i know how to do it but it wont work, nothing i do works.

hymm, interesting. Try deleting cache for settings as per the later portion of this video: https://www.youtube.com/watch?v=94qQbr_J9cw

next resort is update to android nougat

I tried clearing the data of the setting app as the video said but the developer options still will not "unlock" no matter how many times i tap the build number.

-WillW- how do i do that?

try https://www.samsung.com/us/support/answer/ANS00050677/. Under the update via computer section

if that doesnt work you can use Odin: https://forum.xda-developers.com/tab-4/general/guide-how-to-restore-stock-firmware-t2979006

It says you need the usb debugging option enabled but its in the developer options witch i cannot access.

if you want to install a stock rom via odin, you dont need usb debugging to be on, just boot into odin/download mode and flash a stock rom, then do whatever you need.

While i do know alot about mobile devices were getting into uncharted territory for me so i would need a step by step tutorial if im going to do this.

thats what the XDA guide is doing. We are essentially wiping your android  and reinstalling the newest from samsung

Okay but i also dont know anything about backing up my device without a pc.

samsung switch can back up using a PC, I dont think you need USB debugging enabled for that

Unfortunately i dont own a PC.

Can you access recovery if yes then click apply update via adb...then do a
Fastboot into a custom adb enabled recovery like twrp or cwm
$ fastboot boot /tmp/cwm.zip

Or
$fastboot flash recover twrp.img

After booting into recovery you can have your ADB enable also then you can root your device

But adb  requires USB debugging mode enabled, which is in the dev options. Anyways he is at a dead end.

Sounds like a good plan but unfortunately i dont really understand what most of that means.

Samsung devices have no fastboot.

I do not know how to access recovery mode, but im sure i can figure it out.


text:
How to know 3g DNS setting on Android?
I want to know what is the DNS configuration of the 3G connection of my Android. Only to know, not to change (yet).

I managed to install ConnectBot on my device.
I can get DNS information by using getprop | grep dns


text:
Contacts not being displayed in contact list but appears when trying to save a contact
I have Lenovo A6000+ smartphone. About 100 contacts have been removed when trying to backup contacts on SD card. But when I enter the phone no. of the removed contact, it reappears again in the contact list.
what is the reason for this and how may this be resolved?

@parthu_panther Editing is OK. But where is the solution...

You can try out with any contacts app available in play store. Does the problem continue with it?

See if anything has changed in contact display settings.
go to settings>contacts>contacts to display>and select "all"
Now it should show all your contacts.

"ALL" is selected already

When you find a contact and press on it, where is it saved to? In this screenshot you'll see that the contact is saved to Google contacts and WhatsApp. Which icons do you see in place of the one in the screenshot? See where it says connected via?

Also, do new contacts show up fine? And what happens when you edit this hidden contact, does it show up after that?


text:
Casper Via V6X Bricked. Can't Boot Into Recovery Mode
I've an Android device, Casper Via V6X.
The device is not booting. I get the vibration and see the logo of the device but then nothing happens. When the device is closed and plugged in, it shows that battery is charging.
I also tried to boot into recovery mode with Volume Up + Power, Volume Down + Power, Volume Up + Volume Down + Power button but still got the short vibrate and logo, then nothing.
I've tried to access to device through ADB but as I expected since the device is closed, my computer can't access the device so ADB always fails to connect to device.
Any suggestions?
Edit: Seems like device is bricked. I've found a ROM and some Qualcomm softwares and tried to connect to device. And then I've flashed it. The console logged that download was successfull and finished. The guides that I've followed claimed that if you see this message that means process is completed so you can run your device. But still, it's not booting.

I think you need to flash a ROM so the phone can boot up again.

Any suggestions with this? See my edited question please.

All my searches return results in Turkish, so I can't really help. Try searching for ROM and flashing guide

See if you can recognize the device through fastboot. adb only sees the device if you enable it in recovery or if the device is booted into normal system.

I've tried fastbook oem unlock and it said waiting for any device. Nothing happened.

You said you tried to flash stock rom, can you paste the link you followed? You also said you cannot boot to recovery, so I think you will need to flash stock recovery from the bootloader before you flash ROM.


text:
entered recovery mode by mistake stuck in boot loop
I have accidentally put my phone into recovery mode, and I cannot exit from it. Rebooting doesn't solve anything, it opens to recovery mode again.
I believe that, it happened since I hold the power button too long and accidentally pressed volume button at the same time.
I have checked a lot but couldn't find how to fix this. Since I haven't backed up my pictures yet, I want to know that if there is a way to exit from this mode without deleting my pictures(data)? I couldn't understand if installing from adb (I don't know what it does) or fastboot to reboot will delete my data? In addition, I haven't been able to install the latest update since my phone didn't have enough memory. Could this situation be related to that? Sorry for asking lot of questions but I am really worried since I don't have any service to have it checked up .
P.S:my volume button is not stuck.

Install adb  & fastboot drivers:
https://forum.xda-developers.com/showthread.php?t=2588979
then plug in your phone and run in the command line
fastboot devices

*if it says fastboot cannot be found, then change directories until you are in the same directory as fastboot.exe, or add it as an env variable
if you see your device listed, run
fastboot reboot

that will try to reboot the device normally.

How the phone can be detected without USB debugging enabled? Can you explain how to make it  detected from the recovery?

Even more, how is it supposed to detect the device at all if it is in recovery mode? Fastboot only works in bootloader mode.

It can be detected in ADB Sideload mode though. But I'm not sure if the reboot command will work...

Sorry, boot into bootloader mode. Then run the fastboot commands. You dont need usb debugging to use fastboot in bootloader.


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Init.d Script won't work to keep value
I was try to change some value like vm, lowmemorykiller, adj, and net using shell script, then save it to init.d folder and execute it as root.
after reboot, it always back to default.
And i was trying to do this :
adding this command :
busybox sysctl -w or sysctl -e -w
busybox chmod 755 or 777 /path
mount -o remount, rw/system
and doing this :
set permission to 755/777
give a number in name like 99userinit
i have busybox installed and init.d support too
but it still can't changes, so what shoud i do ???

Assuming you are using the classic Android Emulator (so not the newer, ranchu version), any changes you make on the /system partition will be discarded on reboot by default.
To work around this, you should:

Perform any needed operations.
Backup the temporary system image.
On Linux, this is located under /tmp/android-[YOUR_USERNAME]/ and is a file called emulator-[SOMETHING].
On Windows it should be under C:\Users\[YOUR_USERNAME]\AppData\Local\Temp\AndroidEmulator\[RANDOM_FILE_NAME.tmp] (although I have not checked the latter).
Copy this file to a handy location, as it is removed when the emulator is killed.
Restart the emulator with the new system image (backup the original image, rename the new one to system.img and place it in the avd directory, then start the emulator).

Source


text:
Can I receive pending messages of WhatsApp after I reactivate my account on new phone?
Can I receive pending (undelivered) messages from WhatsApp that were in my dead phone but still pending because of the dead phone when I reactivate my account on the new phone? Can I receive it back after re-installing it on the new phone?

As long as you register your phone number on a new device within 45 days, you will receive all pending messages.
After 45 days, registering WhatsApp on a new device will be as if you never had WhatsApp before, no groups, no pending messages, no profile picture.
(But you will still be able to retrieve your old messages from Google drive (not the pending ones though))


text:
How do I bridge Android guest network traffic?
I need a way to direct all traffic from an ARM Android guest to a virtual bridge on the host.
I'm using the Android emulator binaries (built from source) and Android images built from the AOSP repository.
What I have tried:

Starting the emulator with qemu parameters to create a NIC and connect it to a host bridge (my-interface) gives a Segmentation Fault.
emulator -avd [...] -qemu -net nic -net tap,ifname=my-interface

Disabling the adbd service inside the guest did not solve the above.

From what I understand, the system uses the default interface (eth0, which is a default qemu user mode interface) for adb, which might be why I cannot replace it with a TAP interface.
Is there a way I can work around this?

you can see my answer to this post: https://android.stackexchange.com/questions/191004/how-to-use-net-tap-with-android-sdk-emulator/191743#191743 and some resulting issues that I have found: https://android.stackexchange.com/questions/191522/connect-android-emulator-to-lan


text:
Data Usage by Apps That Aren't Running
I have a OnePlus 3 and am using a product called GlassWire to monitor my data activity.  Recently it is showing that certain of my apps are using the network even though they are not running.  By this I don't mean not running in the foreground, I mean they're not started at all.
Could someone explain how this could be?
If you need me to be more specific about anything please let me know.
Thank you.

I am not explaining how this can be vividly, but background processes do sometimes connect to data. You can use DataEye. I've been using this app. It helps control data usage and blocks unwanted background data.

Restrict background data for those apps..

Thank you, however I know how to restrict data usage for the apps.  My question was, why is it necessary if the app isn't running at all?  Can an app start up spontaneously without my knowledge?  Why would it do that surreptitiously?  btw, this isn't a background process, it's a process that isn't running.

@PAnderson Apps have background process or services! So even if you don't lunch them, they keep running. Example: How does a mail client fetch new mails even if you don't open it?

Thank you.  I guess it was sort of a "duh" question.  I also now see the option in Developer Options to see the services and processes that are currently running (turns out pretty much everything).


text:
Can a Xiaomi / MIUI phone bet set to use dd/mm date format?
I have a Redmi 4A that I bought while in China a few months ago.
It works great in English but seems to only offer a choice of only 12- vs. 24-hour time format and American date format, mm/dd/yyyy.
For all English speakers who aren't American this format is very confusing. All my other devices let me change to dd/mm/yyyy format. But so far I can't find a way to do this on my phone.
Android version is 6.0.1 MMB29M and MIUI version is 8.5.4.0(MCCCNED)

It's less Xiaomi than Android 6, which eliminated the corresponding setting from the settings pages unfortunately. The argument is obviously that those formats are bound to the region, and thus shall be chosen by the language you pick (English/US vs. English/UK,NZ,whatever).
What they obviously forgot is that the number of combinations is limited. No way to chose e.g. English/DE that way, to have English language with German date/time & number formats. Or that one user prefers the year in dates being 2 digit while another wants 4… I was looking for a better solution for weeks, but couldn't find it.
Also see: How to change date and time format on Marshmallow?


text:
A confused senior citizen
I have an Android Samsung Galaxy J5 phone with SIM card slot No 1 with a Reliance Jio sim and SIM card slot no 2 with a BSNL 4G SIM.
On my BSNL line I do not have data but only for incoming/outgoing calls and other usual applications. I also have roaming and international calls.
On my JIO line I have usual Tariff facilities including data and national roaming.
What do I do to get the maximum out of my two SIM cards and what settings do I put for them??
Please advise as I am really confused.

What do you mean by getting maximum out of SIM cards? Moreover, JIO tariff and prime features are confined to India, so it is better if you delete those parts.

What do I do to get the maximum out of my two SIM cards and what settings do I put for them?

JIO only has a 4G VoLTE network and wouldn't work in 2G/3G. Does your phone support LTE + LTE may not be supported in your Galaxy J5. See if you can manually set your network and search for the BSNL sim from "Dual SIM settings".

On my BSNL line I do not have data but only for incoming/outgoing calls and other usual applications.

You will have to switch primary SIM from JIO to BSNL for this as your phone doesn't support LTE+LTE. The JIO sim will probably lose signal when you switch BSNL to be the main SIM.
Also, you cannot use Mobile Data for both SIMs at the same time

Your sim cards should work out of the box. You only need now than one if you travel from one county to another or one service area to another to avoid roaming charges. Your sim card allows you to connect to your network operator for regular phone calls. But to get higher speeds for browsing the internet look into WiFi, you will need to connect to a router.

How does that address the question of assigning wanted functionality to specific SIM cards? And obviously noone carries a WiFi router along while on the street (but uses it at home or in the office, when available). This question was specific to SIM cards and mobile traffic.


text:
How to pass all throttled data traffic to an unthrottled port and browse internet at full speed
There are multiple TCP/UDP based VPN apps which can provide free internet. I'm no expert in this field but according to what I understand is that these apps can work if you are able to browse at least one website without any internet plan. They pass all the normal internet traffic through that one website so that your operator thinks you are still browsing that one free website.
Can someone throw some light on how this process exactly works and can I use it to make my internet work faster because when I exhaust my data limit still some websites work at full speed.

I don't see how this is possible, this isn't how VPN's work... They REQUIRE an internet connection to make the tunnel from your device to their VPN server, without a valid internet connection you cannot build the VPN tunnel.

"if you are able to browse at least one website without any internet plan" Many operators allow their official homepage or webportal address to be reached to show ads without having any internet connection. VPN apps use these addresses as host and with appropriate port they can tunnel whole internet traffic thru it. Related info here https://dnstunnel.de

Yeah, but you are talking about captive portal bypass via DNS remapping or IP routing, completely different... years ago those types of restrictions only stopped you from resolving DNS through public servers, it is completely different now with legitimate routing restrictions in modern WiFi captive portal systems. You are talking about a completely different scenario when you have service to access your carriers website but not the rest of the internet. Try it, open a terminal and see if you can ping 8.8.8.8 or another IP, if you can this might work, but I doubt it will.


text:
How do I mount an external USB flash drive?
I have a SanDisk 32GB external flash drive I bought six years ago which I used to back up files from my PC. At the moment I no longer have access to as PC, but would like to mount my USB drive and use a file manager app to move my pictures, videos, WhatsApp files and browser files to the external mass storage.
The mass storage device (USB flash card) comes with a standard full USB port. The device, has a standard micro USB port, where I usually plug my charger.
So, do I need an OTG (on-the-go) cable? Would this work as a physical adapter?
 Would the OTG cable do anything else besides convert micro USB to standard USB?
Do I need an app to do the mounting or does the OS do everything? Can I install apps on the external USB flash drive. I ask because on android 4.4 there was a limitation and many apps could not be installed on an external micro-SD card plugged into the back or side of the phone.
I am running Android 6.0 on a cheap Alcatel phone.

Do I need an app to do the mounting or does the OS do everything?

No, you don't need any extra app to connect the USB drive, the OS will detect and mount the USB drive automatically, if the file system is compatible. In case your file manager fails to detect the drive, you can use apps from Play Store that come with this feature.

Would this work as a physical adapter.

Yes, a USB-OTG cable is merely an adapter to connect the pins of micro-USB to ordinary USB.

Would the OTG cable do anything else besides convert micro USB to standard USB?

No, but keep in mind that unlike PCs, your phone might not provide enough power to drive hardware that requires that power (like hard drives), so you might need to use a powered USB hub for such applications.

Can I install apps on the external USB flash drive.

No, unfortunately you can't. Just like with external micro-SD cards, support for installing apps on external media is best described as "non-existent" (there is adoptable storage, though). Installing app on SD card often just moves the app to the user's data partition which has been originally provided by an SD card but was later integrated into the storage of the device itself.

You've given a better and full answer than mine. I'll edit yours to incorporate mine, and then delete mine, so that the OP can accept one answer.

@WrichikBasu I have accepted the edit after improving it a bit to fit my experience (I regularly use USB-OTG).

Thanks for your answer. If you could improve the last part on installing apps on external cards I will accept your answer.

So I guess its best to purchase an OTG cable which can be powered individually. Thanks.

If your device supports otg then plug it in ...it is very simple just plug your usb into otg then otg into device..
Have fun..
Note: some ntfs device doesnt work with otg...so you have to format your usb with fat or fat32 ...
Good day

Good point with format type! Thank you!


text:
Why is 180 rotation disabled on android devices?
I managed to get around the limitation using an app (Rotation Lock Adaptive) but meanwhile it still has me stumped as to why you can't use a tablet upside down (I prefer to have usb cable out of way when changing or tethered) any ideas?

It's not "on Android devices", it's "on some Android devices". The device manufacturer chooses whether to allow this when they do the software integration.

Ok maybe not all but the majority (I don't recall a device I've owned that didn't).. I'm just wondering about the rationale


text:
Trouble installing SwiftKey via APKPure
I don't have a Google account and use APKPure (and F-Droid) to get most apps I need. Now, there are a few apps which, after download, refuse to install - they give me the "App not installed" error when I try to install them from within the APKPure interface. Right now I'm seeing this with the SwiftKey Keyboard application: I already use it, and I'm trying to install an upgrade of it but getting that error.

How can I determine why I'm getting the "App not installed" message?
Should I try installing in "Safe Mode"? I've heard about it but don't yet know how to get into it.
If I want to try and install manually - where do I find the APK file(s) for my app?

Additional informations:

I'm using a Xiaomi Redmi 3S with Android version 6.0.1.
SwiftKey is already installed and is in use; but just to be sure, I replaced it with another keyboard as the chose/active keyboard app and the results are the same.
The APK file seems to be this one (assuming I get the same file from my desktop and from my APKPure app on my Android device).
$ apksigner verify SwiftKey\ Keyboard_v6.6.9.32_apkpure.com.apk
WARNING: META-INF/DEPENDENCIES not protected by signature. Unauthorized modifications to this JAR entry will not be detected. Delete or move the entry outside of META-INF/.

Related: 'App not Installed' Error on Android What Android version does your device run? Did you have the app (here: Swiftkey) installed before?

@Izzy: See edit.

Thanks! Next, could you check that Swiftkey APK: what's the minimum Android version required? If you have the chance running it via apksigner verify swiftkey.apk, could it be it is missing a v1 signature and has a v2 sig only (you should also be able to guess that by opening the APK with a ZIP manager and look into the META-INF/ directory. If there's a v1 sig, there should be 2 cert files. If not, it cannot install on Android <7).

@Izzy: See edit. Does that fit your second option?

It indirectly answers that: As v2 protects the entire APK automatically, a single unprotected file being reported means there must be a v1 signature. OK, one case ruled out, the signature seems to be OK. Requirements on APKPure state "Android 4.1+", so the second possibility (the APK being for 7+ only) can be buried as well. One point still open: Was the app already installed on your device before? Also, could you check logcat while trying the install? That might give some further clues.

@Izzy: Already said that it was, but see edit. Also - what is logcat? (going to look that up.)

Then it might be that either it wasn't cleanly uninstalled before (happens sometimes: if e.g. the app's directory in /data/data remains, that might result in an UID mismatch on a later install, or signatures might collide if eg. one was installed from F-Droid and the other not). As for logcat, take a look at our logging tag-wiki.

@Izzy: Well, it was never uninstalled, i.e. I still use it after the installation fails. However, the initial installation came with the phone, so maybe that could be the reason.

The log should then reveal a signature mismatch. Or whatever is the reason if that's not the one.

@Izzy: Using CatLog, I'm told that I can't access other apps' log without root privileges - and I am hesitant to root my device (something I haven't done before). Do you think uninstalling and re-installing the newer version should work?

To the first part: use adb logcat (take a look at our adb tag-wiki if you haven't installed that yet; there are also links for minimal installations). To the second part: Maybe – depends on what the underlying issue is, so I'd first consult logcat.

Following @Izzy's patient advice in the comments, I got impatient and finally resolved this.
The reason for "App not installed" in OP's case
The pre-installed version of the SwiftKey Keyboard app had some sort of incompatibility with more recent versions - a "signature mismatch" - preventing an upgrade from the former to the latter.
Should I try installing in "Safe Mode"?
Not relevant in this case.
So how do I upgrade SwiftKey?
Uninstall SwiftKey (just the main package; there may be auxiliary packages) and install the new version.### How to determine why you get "App not installed" generally
It's tricky. What you can do is have a look at the "logs":

Install a log viewer app like CatLog
Install something like Termux (or an SSH server, then SSH into your phone)
In a terminal, run adb logcat
Try installing SwiftKey
Have a look at the what you get in the log

You need to redirect the log output into a text file if you can't scroll your terminal well enough.


text:
Enable OK Google detection when connected to car bluetooth
I have set "OK Google" detection to "in Google app" only. I don't want Google to be listening all the time.
However, I would like "OK Google" detection to work when I'm driving. This means that the phone's bluetooth is connected to the audio receiver in the car.
Is there a way to turn OK google detection when my phone connects to this specific bluetooth device and off again when I disconnect?
If not, is it possible to turn it on when bluetooth is turned on? (I rarely use bluetooth for anything else.)


text:
How can I efficiently move 40+GByte of mp3 data to my phone?
My entire music library is sitting on a server that I access through SSH (could be setup for HTTP) and I would like to copy it to my Xioami Mi A1 (running Nougat).
What would be the best way to accomplish this without using an SD card?  I installed Termux, and an rsync client, but:

I don't know the location of where I should download too, and
there seems to be a permission issue anywhere outside Termux's home directory ('whoami' reports my user credentials as "u0_a###")

I would like to transfer the music to the "proper" directory (not just the downloads directory).
With 50+G of unused storage space, I'd really like to make use of it.

The default path for music is typically /sdcard/Music. Don't be fooled by the sdcard in the path, that's a relic of the past from a time where devices didn't feature their own external storage.
For Termux to work correctly in this regard, you have to manually grant read/write permissions to your "SD card" to Termux. Do that in the Settings app under the point of app permissions (exact naming may differ by manufacturer).
The user identifier is the one of the app, because on Android every app gets its own separate user to protect the data of each app.
I have no experience with rsync but I can imagine it will work, if you just switch into the /sdcard/Music directory and use rsync from there.
Termux should have all the tools for doing what you are trying to achieve.

File copying over SSH, with scp, is quite fast, depending on your network environment, and is more reliable than adb push and MTP.
In fact, copying over network is my primary choice for bunches of files.

Agreed.  But you neglected to address my only two points: permissions and proper location.


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What's the problem with my battery?
Well some people here have came across this question I posted few days ago. I want to inform them that I had to reflash my phone (and I'll edit the details there as recommended by @Izzy)
Device: Lenovo Vibe C
Android: Lollipop 5.1.1
So now after a reflash I tried to root my phone again by the KingRoot app. It went fine upto 24% when I thought of disconnecting the router which it was connected to. The app showed me that a file could not be downloaded and then as it happens (on this device particularly during rooting, the phone shut down). Usually in such cases I remove the battery and reinsert it and boot the phone to continue with the root procedure but this time it did not happen. I tried twice but failed. It was after that I removed the battery for about 30s that it booted up again. After the boot the battery indicator in status bar was working in a strange manner. It first showed 50% then the next instant dropped to 2%, and remained there for about 1 hour. Then after I plugged the charger it again jumped back to 50%. In spite of this I charged the phone for rest of the evening. When I again started using it some minutes back, it started behaving strangely again. Initially the charge was 88% then it jumped down to 50% then to 69% and so on. Here are some statistical screen shots taken from 3C Toolbox.

This one from the battery section of settings app. See the ups and downs at the end.

And another problem, I see this annoying notification even when my battery is at normal temperature.

My device is 2 years old so there are no issues with the battery itself I think it is the OS files that are causing the disturbance. I think this would be a silly question (as it is not possible) Did this happen due to the kingRoot app? What may be the cause, please help me out.
EDIT
The battery files of the OS, I think these (the current_now and the temp_cool ones) probably have been corrupted in some way. Can they be replaced with files downloaded from the internet(if any). Please help

It seems (though I will not confirm as I'm no developer) that the failure of the root process has resulted in the corruption of files in the OS partition, due to which these are happening. The battery history screenshot looks dangerous with so many spikes, with such a great slope, which indicates that there is a problem as no battery can be charged so fast. Unfortunately, I've got  no solution for this, but will keep looking upon this question to see if someone has a solution.

@WrichikBasu But my question is how. The root process installs an su binary file in /system/bin folder but how can it affect /sys/class/devices/power_supply/battery folder. They are way apart.

As I said, I'm not a developer, so whatever I said was a "may be".

@WrichikBasu I respect your argument, and I too thought that, but I'm just confused. How can this happen. I've rooted this device two times before, such things never happened. I think I have to reflash the rom again.


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Phone reception puzzle
My wife and I both have 2013 vintage moto g phones using the GiffGaff network. My phone gets decent enough reception, whereas my wife struggles to get reception most of the time (for instance see is currently talking on my phone because her phone didn't get reception). I just wondered whether there was a possible software reason for the difference in performance? Or is it likely that my wife has just dropped it and broken/weakened something inside?

I had that problem when I was in the UK using a giffgaff SIM on my Moto (Marshmallow). My daughter's phone was getting a signal when I couldn't get one bar. Checking my APN settings to ensure they were as giffgaff intended solved the problem.
Assuming you both have exactly the same set up otherwise, if the APN setting is different or non-existent on one of the phones, your wife's phone may be trying to connect to the wrong network (or, if she has roaming disabled, she may not have a network to connect to).
First guess? Check APN settings are what giffgaff gave as the settings. It may be that hers are different from yours because for whatever reason giffgaff had the SIM cards set to use different networks. So check the text which provided that information on her phone as well as yours.


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How does Android keeps track of how much battery each specific apps used?
How does Android keeps track of how much battery each specific apps used?
For example, if you go to battery usage on android phone, it will say something like:

Display 70%
Whatsapp 25%
Browser 3%

etc.
Is this done by battery manager?
And how accurate is this values computed, I am trying to come up with an app that can accurately measure how much battery each apps specifically consume.

There will be low level APIs that Android uses when computing battery stats.

I am trying to come up with an app that can accurately measure how much battery each apps specifically comsume.

Although this sub isn't for development related questions, check out Batterystats on how to implement battery collection stats.


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Routing ringtone through headset
I just bought a Samsung Galaxy S8+. Everything is working great, but there is one little thing I can't seem to figure out and that is the ringtone uses only the speakers.
Can I route the ringtone through a headset when it is connected?

Sadly there's no way to do that presently. There's a very old question here that tried achieving it in Android 2.2. You can try setting up Tasker to do it for you. Android doesn't have anything built in for this as far I know.

I suspected as much. Thank you for your response. I will look into Tasker.

Did you ever resolve your question?
It appears that Samsung Sound Assistant can do what you want.
However, you might want to check my question about this - just so you are aware of the problem I am having.


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How to add an APN when "Mobile networks" setting is disabled?
I've got an unrooted Samsung Galaxy S5 from T-Mobile running Marshmallow (6.0.1), and am trying to add an APN so as to use the phone with FreedomPop. I've installed the FP SIM card and entered the unlock code. The next step is to add an APN for FP, but when I try to access the relevant settings (Settings→Connections→More networks→Mobile networks), "Mobile networks" is disabled (grey text, tapping has no effect). How can I enable the settings (the preferable route), or, failing that, add an APN in another way? (So far, the other methods I've seen require other steps (e.g. rooting the phone) which have their own roadblocks.)
"Mobile networks" remains disabled after switching back to the T-Mobile SIM card. The phone lists the ICCID for each card when inserted.

Does the phone recognize the Sim? Cuz I've had a time when my Sim wasn't activated and apn settings didn't work. But if it doesn't work with other Sim cards either, then i guess it's blocked by the carrier

Besides, if the card is not accepted by the device, the APN will be useless. Android choses "usable" APNs by the MCC and MNC detected from the carrier signal, so the "base signal" must be there to begin with.

The phone appears to recognize the SIM. At least, the SIM's ICCID is listed in device settings, and doesn't display any error messages regarding the SIM.


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Transfer file from Xiaomi Redmi 4A to Mac
I have a Xiaomi Redmi 4A I bought in China a few months ago still running the Chinese ROM.

Android version is 6.0.1 MMB29M
MIUI version is MIUI 8.5 | Stable 8.5.4.0(MCCCNED)
Laptop is MacBook Air running Sierra

The two are paired and I can connect easily. I can send files from the Mac to the phone using Bluetooth File Exchange.
I cannot use the Mac's "Browse files on device" feature because "The device does not have the necessary services".
From the phone's Bluetooth settings I can connect to the Mac but can't find any way to send a file. I can't find any app or tool on the phone for sending files or using Bluetooth. I've looked through the UI, in the Tools section, looked in the phone's storage using Explorer, and I've tried searching the phone for "transfer", "send", and "bluetooth".
I can transfer in both directions using a USB cable.
For this question I'm looking for a solution without any 3rd party apps. If it's not possible without such an app, that's an acceptable answer. I'm looking for non-USB solutions for this question.

Sorry didn't get your question initially because of "I'm not looking for non-USB solutions for this question." sentence.
As for Bluetooth solution - Open Mac->Settings->Bluetooth on your Mac, there will be checkbox "Show Bluetooth in menu", Bluetooth icon will appear near your clock in top right corner. Click it, there will be "Send files to device". Click it, choose file, choose your device. You transfered file from Mac to Phone.
As for reverse direction - open any File Explorer application on your phone (stock explorer, ES, whatever), select file you want to transfer, long tap it, select "Share", select "Bluetooth", select your Mac Bluetooth name. You done.
Sorry for my English and maybe not very accurate menu item names - I am Russian and have Russian Mac OS and Android.

Oops thanks for pointing out that thinko! I'll fix that right away ... Mac to phone works no problems. I thought I mentioned in my question but maybe I made multiple thinkos (-: Will try the long-tap solution ASAP.

If only there was a Redmi 4A manual, an MIUI manual, or an Android manual somewhere to learn the basic! (-:

Well this worked when I first tried it after reading the answer. But now it fails every time. Same phone and laptop. I've tried sending photos taken with the camera from Gallery and Explorer. The error message is "Request can't be handled correctly."

Please check if you have Bluetooth enabled both on your Mac and on your Phone. This is most common reason of such errors.

Yes I checked over and over and sent a file in the other direction to verify. Just a few minutes ago it did work again for the first time in a while though...

Here are the ways you can transfer data between your Android phone to Mac. https://101android.com/transfer-data-android-to-mac/

Note: If you are ok with third party app then,
There is an app called Shareit available for this purpose.
It is cross platform (supports mac, pc, ios, android and windows phone).
Uses wifi for file transfer, so its very fast. Please check it out.
Shareit Official website

I don't have Wi-Fi at home. I do have Shareit. I find it frustrating because it seems to work perfectly sometimes and not at all at other times. Depending which pair of devices I'm using and what Wi-Fi signal I'm on.

Here is an official Android utility to transfer files:
https://www.android.com/filetransfer/
As a pity there is no other non 3rd-party options for Mac.

As mentioned in my question, I can transfer files fine with the USB cable. (Using either AFT or a couple of other apps, though AFT wasn't working when I first tried it in China.)


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Galaxy S8: Set default app for left swipe?
Is it possible to set a default app to open on left swipe on Home screen? Currently Bixby app opens on left swipe, I would like to change it to some other app.

You can either use Bixby Button Remapper or disable Bixby on left Swipe:

Enter edit mode for Galaxy S8 home screen(long tap on homescreen)
Switch to Bixby Home page
In the Bixby Home (Hello Bixby)  page, you can find the switch in the top right

Currently it is only possible to change the app on left swipe by installing an app called Bixby Remapper.


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TWRP recovery installed but not opening
I have Vivo y15s , I rooted my phone with fastboot (oem unlock)
I installed TWRP recovery.img using fastboot
But
My phone is not starting and TWRP recovery mode is not opening.
Only Fast Boot mode is working..

did you installed latest twrp for your device?

My suspicion is that you might have flashed the wrong TWRP image. TWRP images are specific per device. Look for your device here:
https://twrp.me/Devices/
If you find the correct one, then reflash stock OS, then oem unlock, then flash new recovery.


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What is this screen and how do I get rid of it?
Today my pixel 2 randomly decided to show this screen after I log in.

Where did it come from and how do I eliminate the extra step before being able to access my phone?

It might be from touch pal keyboard.You can now turn this latest intrusive Touchpal off via 'settings' > 'look and feel' > 'lucky locker. Or look in touch pla keyboard settings

Do you refer to the lower part of the screen, the upper part, or all of it? Installed anything lately – especially any app related to "battery optimization"? Taking a closer look at the upper-right corner: @Abochur seems to have hit the nail. A search for "Lucky Locker" turns up tons of cry on "Stop Lucky Locker, TouchPal!"

I guess it's UC Browser..

Many Android applications have junk adware like this. Check what apps you installed recently, one of them may be the culprit.

That's the sort of thing you get from an app that comes with ads. Check what apps you've recently installed and force close the offending app to remove the screen.

What does that have to do with VPN? It's an ad that could come from your favorite torch app or your latest game as well.

Just an example of an app you might install - I used that example since I've had a similar thing from a VPN app.

Maybe just make that "an app that comes with ads"? Otherwise it always looks as if VPN apps would be especially affected by this, which definitely is not the case. Black sheep are everywhere. And in the OP's case, I'd say that black sheep is identified, and not a VPN ;)


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adbfs-rootless: "Transport endpoint is not connected"
I was looking for a way to mount my phone in Linux, over USB, and I came across a recommendation to use adbfs. I was able to download the files to a directory and run make, and I created a subdirectory called mnt.
When I run ./adbfs mnt I get the output --*-- exec_command: adb shell "ls".
When I try to navigate to the directory, I get Transport endpoint is not connected.
I know I am connected to the phone because when I run adb shell I can access the phone and navigate through its files.

Having found my recommendation in that answer, have you followed the link and checked the issues? You're probably running Android 7 or above, right? See: Doesn't work on Nexus 5 after upgrade to Android 7.0: Transport endpoint is not connected – it's a known issue and currently unsolved. That issue holds a "dirty work-around", though, if you're interested.


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how can I prevent a factory reset of Samsung android device?
The Samsung android table I got for my kid has a "Guest Account" feature that lets anyone in without a password. Kind of defeating the point of the password feature that keeps a 7 year old kid out at bedtime.
so I ran:
adb shell settings put global guest_user_enabled 0

with a USB cable attached and it worked. Now the guest account is gone. But all the 7 year old has to do is go into setting and do a factory reset and that will go back to
adb shell settings put global guest_user_enabled 1

Right?
How do I win this password war? I'm older. I have to win.

I think I found the answer. I have to create a restricted account called "kids" and always hand him the tablet logged into this account which cannot reset the device. But If I ever give it to him logged in as the admin account, he could.

is this for many uses, multiple programs or just one single application, because if it's one single application, you can use screen pinning to pin an application to the screen for privacy.. this will lock the phone from having access to any other app while pinned ! ... this can be found in Security or privacy settings.....   Else a restricted guest account works best

I'd say this is a losing war - the kid could always just boot the device into recovery mode and factory reset from there, and that's not something you can prevent with anything software - it isn't even a part of Android OS. Granted, if you log into a Google account prior to that, after the reset he'd be asked to enter the password to that account before using it (FRP), which then requires you to intervene, but this is then a lose-lose situation, where he didn't get to use the tablet but you also get some hassle.


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How to install Google Play Services without through Play Store in Redmi 3?
A bunch of my apps ask me to install Google Play Services but my Play Store won't start since the service is missing.

Try downloading play services apk and install it. https://www.apkmirror.com/apk/google-inc/google-play-services/

Have you checked with our google-play-store tag-wiki yet? Then maybe you've seen How can I install the Google Apps Package (Play Store, …) on my Android device?

Just install Google Play Services from a trusted website. You can download it from apkmirror.com, but it is important to choose the right version for your smartphone. Read the minimum Android version and architecture (arm/arm64/x86).
After that you need to install the APK. Well, sometimes the Play Services don't work after the installation.
In my experience, it's caused when the Android doesn't have Google Services Framework, Google Contacts Sync, and Google Account Manager app. If your phone doesn't have all the Google apps (usually with MOD ROM or MIUI ROM) you have to install them first. Just find them on the website I mentioned above.

You have to install it from third party sources. Such as

Aurora store. fdroid link Open source and uses googles APIs to download apps from google.
or you can use this site to download play service. Evoji

Sometimes Chinese variants don't have Google Play Services installed in the first place because they cannot work in there.

Ops redmi 3 runs android 5 .very old and yeah some of them don't have by default.


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How hike messenger is auto inviting WhatsApp group users and importing WhatsApp chats?
I recently witnessed hike (beta) auto inviting friends via WhatsApp & importing WhatsApp chats to hike on my friend's non-rooted phone. Till then, I was under the impression that inter app data access on a non-rooted android phone was pretty much non existent unless you explicitly grant them.
Here the only extra thing hike requests is android accessibility permissions (notification & window). How is hike achieving this?
Even the Accessibility Api is quite restrictive & does not allow simulating touch events. And while importing hike shows one view written encrypting data & doesn't even bring up WhatsApp to front to read window content.

Can you share some screenshot? (Please hide any sensitive or personal information from the screenshot.)

Related Question: Can Hike messenger steal our whatsapp data

Hm.. someone is getting bothered.. https://www.xda-developers.com/google-threatening-removal-accessibility-services-play-store/

Seems like simulating touch event is supported. Then they could use this and window content reader to crack the content from other apps. https://stackoverflow.com/questions/39283640/how-does-the-api-24-accessibilityservice-dispatchgesture-method-work


text:
Can an Android device be remotely factory reset using any email ID on the device?
We had created a common ID for the college group and I think someone remotely wiped my phone. Is it possible to do it with the secondary account?

Yes, with Google's find my device you can locate, lock, and ERASE, the phone. So anyone who has access to the accounts connected to your phone is able to erase all your data.
It's made for cases of lost phones where you want to stop the thief from accessing your data.
This feature is automatically enabled on most devices.
All the person would have to do in order to erase all your data, would be going to find my device page, put in the joint email address and password, and press erase and confirm. As simple as that.
It doesn't make a difference if this account is the primary one, or a secondary account.
In the future don't add any accounts to the phone, that others have access to.

I'm surprised it is that way. I thought only the primary account(the one I use on the Play Store) had that privileges. Any way to find out who did this?

The only thing you might be able to see, is which email address was used to wipe your phone, but being that multiple people are using the same account it's most probably impossible to see who did it.

@Yashbhatt, if there is such a thing as ' primary account' it probably good by the first account added to the phone and not the one used in play store. All features are available in all accounts including find my device and erase. Google should definitely warn of this, as I've seen many people share accounts

Exactly. Any way of seeing the IP address of the device which was used to perform the reset?

Sorry I don't know if that's possible :( unless you contact Google support, they might tell you. Or maybe post a new question with a link to here. In the mean time, if I answered your original question correctly, feel free to mark it as such (the "√" next to the answer) so that others know this was "solved". Again sorry this happened to you.

Thanks for the help. Google Support said nothing can be done about it.


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How to stop System update on Firefly intense 5
My phone is Firefly Intense 5 and I received a notification of system update. I accidentally hit it so my phone starts updating. Now, it suddenly turns off because it's low bat.And up until now, it is still updating. The update starts last Wednesday, now it's Friday. Is there any way I can stop it?

Try this:

Go to Settings
Then applications (or app)
Sweep to Running apps
Locate SystemUpdateService then stop it. (click on stop)
Go back to Download apps
Locate Google Play Service and Clear All Data
Now go check at Settings > About > Software update. You should see the update there just don't hit on download.


text:
What is this `adb` utility I keep getting advice to use?
In a bunch of questions on this site I see answers telling us to execute adb shell or adb logcat and so on.
Now, I'm not an entirely clueless user, so I downloaded and installed Termux and have a shell prompt when I can type in commands, but - where does this adb thing come from? Do I download it as an app? It doesn't seem to be installed by default (On a Redmi 3S, Android 6.0.1).
Also, it seems like it's some kind of permission elevator. Is it like su? If not, how is it different?

https://developer.android.com/studio/command-line/adb.html, https://lifehacker.com/the-easiest-way-to-install-androids-adb-and-fastboot-to-1586992378

@RahulGopi: Yes, I just think there could be a succinct answer here on the site.

It's the tool described in our adb tag-wiki, with resources linked – told ya that before I guess :) Remember: Many of our tags have decent wikis :) Also see, here on our very site: What's ADB and why is it used for? How do I install it on my device?

The ADB is used to connect mouses and keyboards to state-of-the-art computers.

About adb
To put it shortly, adb (Android Debug Bridge) is a utility made to be installed on a computer, in order to let it gain a shell on a phone that's either connected via USB cable, or on the same Wi-Fi network.
On certain devices running Android Lollipop (5.1.1) and possibly lower versions of the OS, it was possible to trick a device into connecting to itself, since the adb client came bundled in the phone as well. This is not possible any more because, from Android Marshmallow (6.0) onwards, Google removed the adb binary from the phones to reduce the usable attack surface.
It is possible, though, to manually reintroduce the adb client on a phone, without needing to compile the binary yourself. Refer to the adb tag wiki for more info about this topic, as well as about installation on a computer and general troubleshooting.

Where to get it
Some time ago, in order to obtain adb and another utility, called fastboot, one had to download the full Android SDK from Google, if they wanted an official package. Nowadays, a small, official bundle has become available, as XDA says. It includes binaries for the most common operating systems.

How it works
The adb client, installed on your computer, makes a connection to a plugged or otherwise detectable phone, by means of an internal server. Then, the user will be able to send a variety of commands to the phone itself, which will be listened to by adbd, a daemon residing on the phone.
When using adb, you impersonate the user called shell (UID 2000). This user is special, in that they can grant app permissions and access more information than a simple user. This fact, though, does not mean that adb is the same as su, as the latter lets you impersonate any user.
More info about adb and its workings may be obtained by looking at the official documentation.

Issuing commands from a phone
The majority of commands that can be issued via adb tend to be utilities that come preinstalled in a phone.
In order to access them, you need to install a terminal emulator app on your phone (note that Termux is special, in that it specifies its own PATH, thereby ignoring system binaries). This will, for example, let you issue commands such as logcat directly on your mobile device. Remember to omit the adb prefix, though.
It is worth mentioning that, should you lack root permissions, the range of commands you'll be able to execute and the info you'll be able to access will be significantly less than if using adb, because the UID that invokes them will be the app itself, and apps have less permissions than UID 2000.

Well done! Unfortunately I cannot upvote twice :) // Yeah, our wikis are far too often "unknown quantities". Cannot point there often enough. But including a link in any answer mentioned in it is going a bit far IMHO :) Where it fits (like here: "for further details …"), a good idea. Feel free to go ahead with that – I go ahead for comment cleanup meanwhile :)

@Izzy Good point. Let's wait and see if link spamming is actually needed.

Have my upvote, please.

@iBug I am honored.

Android Debugging Bridge (ADB).
It sends commands over USB or Wifi to an android device. It is typically installed on the computer connected to the device. The ADB client can also be run on device itself however the idea is to remotely debug the device.
It is part of the Android Software Development Kit
You can then use the SDK manager to download platform tools.
There is also a more direct link here in case you're just interested in the
platform tools
ADB Documentation

Wait, if it's not installed on the device, why do people suggest I use it in shells on the device? e.g. in the examples I gave?

Thats a good point. Maybe its more correct to say adb command is the "client" connecting to a android device. The android device can also have the client on it because why not. But thats sorta like running ssh localhost

To be honest the documentation explains all this well: https://developer.android.com/studio/command-line/adb.html


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Can applications predinstalled in system/priv-app be updated via Play Store?
we're trying to make our custom launcher default one in our phone. Since it needs system level permissions (placing widgets) we placed it in system/priv-app, and it finally works ok. Problem is that it is not updateing with new version from Play Store. - we're getting error 505 after downloading update, on start of install process
thank you in advance!
br
Y

To close-voters: though Yuray asks for installing his own app that way, this is not a development question but perfectly on-topic here. Us power users sometimes "convert" regular apps into system apps as well, and still want them updated :) Nice side-effect is e.g. the app surviving a factory-reset (though its data does not).

What permissions did you give it after placing in/system/priv-app? Make sure it's 644. Also, have you placed the apk in a directory having name as the app name?

I met the same problem. The message is "Error -505 while installing com.mycompany.mypackage: INSTALL_FAILED_UPDATE_INCOMPATIBLE: Package com.mycompany.mypackage signatures do not match the previously installed version; ignoring!". Although the signatures do match. @Yuray have you solved the problem?

If the "pre-installed app" uses the same signature as the one on Google Play, it of course can be updated that way – same as e.g. Google Maps and other pre-installed stuff is.
Note that, however, those updates would not be integrated in the ROM, but go into user-space – "overlaying" the pre-installed version. This gives users the advantage of being able to "uninstall updates", but at the cost of "double space" (the original APK remains in /system – not that they could use that space otherwise, though).

we use same signature, if we weren't system could not detect existing update at first place. If we move launcher in regular apps folder, update goes as expected.

@Yuray in that case I see no reason why it shouldn't work.

I found the Google Play is re-signing my package. This used to cause a signatures mismatch. The solution is to install to /system/priv-app/ an apk downloaded from GP (that has been already re-signed).


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Where is Castbox saving the downloads?
Installing the podcast manager Castbox, it has a setting to chose downloads location between internal and external card, but I cannot find them with a file manager. I would like to just copy/paste them on my computer and keep a copy (without the need to download them again on the computer).
Maybe are they trying to avoid the saving of the files?

They saved the file on sdcard > CastBox > channels > xxx > yyy
or on sdcard>Android>data>fm.castbox.audiobook>files>channels>xxx>yyy
xxx is folder of channel usually the unique number of each channel, yyy is file name. But, they stored it without extention of the file, so you cannot play it.
Trick to play it, just rename the file name. Add extention .mp3 on the name.
Example: filename= 24234234
Rename it to 24234234.mp3

Thank you for your answer which put me on the good path. In fact this may by version-specific. On this Marshmallow the location is different (you could add that to your answer and I'll mark it as the solution): sdcard>Android>data>fm.castbox.audiobook>files>channels>xxx>yyy.  But what's more, I was able to reach the files with ES Explorer in Android but not with the file manager of my computer (fm.castbox.audiobook is simply absent there). If I copy one of the files in a different location that my computer normally can access, the file is not accessible by computer.

For the given purpose Castbox is not the best solution. If one must use it in order to transfer a podcast audio file from the phone to a computer, the easiest way that I can see is this: Castbox provides a "share" button for each selected file; sharing it provides a link http://castbox.fm where the podcast can be played and captured/downloaded with a dedicated tool (flashgot, Flash Video Downloader etc)

nice sharing, we can do more if we use computer,

I think there is no use in renaming the file: it can be played without that by android players (in my experience), but there is no way of knowing which file it is before playing it; it also cannot be used effectively but through the Castbox application (such files are NOT accessible by computer).


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Undo remove word from autocorrect
In the newest versions of Android, you can click and hold a suggested predictive/autocorrected word, and drag it into a bin (title "remove") to prevent it from being suggested again.
I accidentally deleted the word "I", so now when I type "i" it doesn't automatically autocorrect to "I".
Two related questions:

I tried shaking my phone to undo the accidental word removal (like I would undo things on an iPhone), but it didn't do anything. Is there a way I could've undone my action immediately after it happened?
Now that it's a few days after the face, how to do I add "I" back to the suggested words without having to completely erase all the things my keyboard has learned about my typing habits?

The solution is to type the deleted word, in your case the "I", many times in a sentence or sentences. Gboard will re-learn about it, and start suggesting it again.

Reset personal data on your keyboard, so your keyboard data will be reset.
Settings > Device > Language and Input > Press the keyboard that you use > clear personal data

I use Gboard (tagged in my question). I don't want to delete all info from my keyboard (also in my question)