text:
Why isn't my Galaxy S8 popping up my Captive Portal login page?
I'm dealing with a Raspberry Pi 3 that is using hostapd to create its own wireless network.
When an Android client first connects to the network, it tries to grab the page http://connectivitycheck.gstatic.com/generate_204 to see if it's behind a client portal. My Raspberry Pi redirects this request to an instance of nginx that it is running, and returns a 302 redirect to my login page.
Because Android didn't get the response it was looking for (an HTTP 204), but got a 302 instead, from what I understand, it's supposed to popup my login page. I've seen this in action using other captive portal hardware.
In my case however, Android just shows a popup that says "Internet may not be available: Connect to another network or turn on Switch to mobile data".
Am I doing something wrong? Is there something specific Android is looking for in the login page before it will make it pop up?
Most of my testing is on my Galaxy S8. I tried it on a friend's S9, and that doesn't work either. Using a Windows 10 laptop though, the login page does popup.

After some digging, it appears it's working now.
When a client tries to access http://connectivitycheck.gstatic.com/generate_204, it needs to use DNS to resolve connectivitycheck.gstatic.com first. I had my dnsmasq setup to look like this:
interface=wlan0
dhcp-range=192.168.30.20,192.168.30.60,255.255.255.0,24h
address=/#/10.45.12.1

Where 10.45.12.1 is just a random IP I chose. It didn't really matter what that IP was, because as soon as the client resolves it to that IP, and tries to get /generate_204 from it, my iptables firewall rules would redirect all requests to nginx running on the Pi.
The only limitation I was aware of was that the IP couldn't be on the same LAN (192.168.30.0/24), or the Pi would try to use ARP to figure out its MAC address, and fail, without making the actual HTTP request.
It turned out that if the IP you are resolving everything to (in my case 10.45.12.1) is a LAN IP, Android won't popup the login page. No idea why.
The fix was to change from:
address=/#/10.45.12.1

to
address=/#/1.2.3.4

where 1.2.3.4 is any PUBLIC LAN IP (an IP outside of the '10.0.0.0/8, 172.16.0.0/12, or 192.168.0.0/16' range). This fixed my problem. Hopefully it fixes someone else's as well.
NOTE: My setup does NOT require the client to ever have internet. They connect to the Pi, and get a page popup for configuration purposes. If you need the device to have internet, which would probably be a more common use case, you probably can't just resolve EVERYTHING to 1.2.3.4 like I do


text:
Read adopted and encrypted SD card with external SD reader?
My Moto G5 sd reader doe not work anymore, and does not read the SD card that was adopted and encrypted. I want to access the sd card to save the data/pics etc.
I thought that I could use an external SD reader, and that the phone would recognize that this is the "internal" card, and hence give access to the data. It does not seem to work: using a file reader like amaze, I see the OTG option, but nothing happens? Which steps could I do? Note my phone is not rooted.
Thanks!
PS: an alternative would be to read the SD card in my Linux machine, and follow the instructions from this page, this one or this guide. My understanding is that I would need to root my phone, and hence potentially loose all data anyway.

you are right, you will lose data when rooting with common bootloader unlocking method. you need root access to get a copy of /data/misc/vold. try to root with Kingoroot (with locked bootloader) or try to get backup with QPST +  HDDRawCopy (no root required) https://forum.xda-developers.com/general/rooting-roms/how-to-backup-qualcomm-phone-root-t3570178

OTG mounts are different from block mounts. the card reader will work with other MicroSD Card, but it can not handle encryption of adopted storage

@alecxs, getting back to this after trying ohter solutions, could you elaborate a little on the Kingoroot vs QPST + HDDRawCopy methods? I'm a very beginner, so a few detailed steps would be very welcome as answer! I am also confused as some posts say roooting would not destroy data? https://android.stackexchange.com/questions/44574/does-rooting-erase-anything Thanks a lot!!!

unlocking bootloader will trigger factory reset, so you need to find a solution with locked bootloader (Kingoroot for rooting / QPST for backup)

source: Stack Exchange

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

sort: votes


text:
Can I use my spare android phone as a Bluetooth speaker?
Actually, I have a spare android phone which is connected to my old speaker system. I wanted to connect to that phone via Bluetooth as if I'm connected to a Bluetooth speaker.
So that, I can route audio to the speakers using any device connected to that spare phone (Indirectly giving the Bluetooth functionality to the old speaker system)
Edit: I saw the related questions, those questions needed any working method that solves it. I don't want to use any third-party app like a music player or anything. I just want the spare android phone to be connected as an audio source to my phone.
The first image is the screenshot of a Bluetooth headphone connected to my phone. I want the same settings as "Media Audio" when I'm connected to spare android phone.

The second image is the screenshot of Bluetooth settings when connected to the android phone which is currently being detected as a phone and I want that to be shown as a Bluetooth Audio device.

Possible duplicate of How to stream music from one android device to another?

@alecxs I've edited the question with the exact requirement.

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


text:
What Is Using Up My Storage/Data on Android Phone?
First, I appreciate that there are lots of similar questions to this online, but they are often so specific that I haven't been able to solve this question myself (through online forums/questions/etc).
I have a phone with 8GBs of internal storage, as can be seen from the first picture below. ~3GBs of this is used up by Android OS; ~5GBs remains, of which I am using ~4.5GBs. (This leads to issues with not being able to update, etc, due to lack of space.)

All reasonable so far. However, as the next picture shows, of that 4.5GBs used (separate to the 3GBs for Android OS), Apps uses ~2.1GBs and Cached data only ~33MBs.
Hopefully my question is clear now:

where is the remaining 2.4GBs?

Internal storage includes all your pictures and downloads, especially WhatsApp Media is wasting space. connect PC via USB (MTP) and move DCIM/Camera folder to your external MicroSD Card

These are actually all stored on my SD card, so this isn't taking up Internal Storage. (Also, WhatsApp Media only had a couple of pictures in it)

You can examine storage usage from terminal with du

in your "about phone" settings, tap "build number" 7x (seven) times to unhide the hidden developer settings, then enable USB-Debugging in developer settings

on PC download platform_tools and busybox binary for your phones cpu architecture (armv7l), rename file "busybox" and copy it to platform_tools folder (i realized toybox is buggy, du works best with busybox)

open cmd.exe and navigate with cd command to folder where adb.exe is. connect the phone to PC with USB cable, then type the following commands (each line for its own)
 adb devices
 adb push busybox /data/local/tmp/
 adb shell
 chmod a+x /data/local/tmp/busybox
 /data/local/tmp/busybox du -acxhd1 /storage/emulated/0

repeat the last command on different folder for your needs. the last digit in parameters controls the depth (see full list for usage)

du is a command line utility for disk usage
CUBOT_KING_KONG:/ $ du --help
BusyBox v1.29.2.YDS (2018-08-01 20:19:15 UTC) multi-call binary.

Usage: du [-aHLdclsxhmk] [FILE]...

Summarize disk space used for each FILE and/or directory

        -a      Show file sizes too
        -L      Follow all symlinks
        -H      Follow symlinks on command line
        -d N    Limit output to directories (and files with -a) of depth < N
        -c      Show grand total
        -l      Count sizes many times if hard linked
        -s      Display only a total for each argument
        -x      Skip directories on different filesystems
        -h      Sizes in human readable format (e.g., 1K 243M 2G)
        -m      Sizes in megabytes
        -k      Sizes in kilobytes (default)

if you don't know your phones cpu architecture you can check the SoC from terminal
adb shell
head /proc/cpuinfo

the busybox binary will remain at your phones temp folder until you delete it
adb shell
rm /data/local/tmp/busybox

Thanks very much @alecxs! How do you know that my cpu architecture is armv7l? And is the architecture for my phone or the computer I am using?

Just a guess. You can check the SoC with adb shell head /proc/cpuinfo

I'm sorry, I've been busy with moving and then being away. I should get to trying this mid September. Sorry for the delay!

It's not clear what Android means by "Apps", which is 2.10 GB. Total size of an app includes its apk file + extra native libraries (if any) + Dalvik cache + obb files + app's data + cache. Data and cache can be on internal (/data) as well as shared private storage (/sdcard/Android). I think the missing 2.4 GB could be apps data if not included in "Apps", or it could be your personal files in /sdcard.
For more details: How disk space is used on Android device?

When I try to update apps, or install apps, it often tells me that I don't have sufficient space, and I have to remove something. This doesn't seem to go with your last sentence about being in /sdcard/. I only have a few apps on the sd card; I'd move more, but they won't allow me (I tried, unsuccessfully, to root my phone)

@SamT on most of the recent devices, /sdcard isn't physically external SD card. /sdcard points to just a directory in internal storage i.e. /data/media/0. Android calls it external storage and divides it into public shared storage and private shared storage. If you read the given link, things will be clarified. Do you have physically external SD card at /sdcard? Which Android version you are on? Which device is yours?

Thanks, but I'm not sure how to find out if I have a physically external SD card at /sdcard. I certainly have a physical SD card in my phone! It's a Motorola MotoE 2nd Generation, running on Android 6.0 -- it's not rooted (I tried, multiple times, but haven't managed)

@SamT output of mount or df is enough to know what's mounted where. Root is not required.

The remaining 2.4 gb is related to the cache section even it appears that the size is so low..
You need to use the app cleaner of Android in the Play Store to get the full information of where the data comes..
For Android like that situation, we don't have full information like statistics of apps usage..

Ok, thanks. On my tablet (also Android), with 16GBs internal, it had something like 3.22GBs of cached stuff; it did surprise me that my phone had only 33MBs...

Unfortunately, this doesn't work: I used a cache cleaner (with thousands of reviews, >4*s average), and it claimed to remove 300MBs, but my internal storage is the same. even if it had removed 300MBs, that's still nearly 2GBs missing...

For the du command mentioned by alecxs, if you want a better interactive gui, you can use ncdu or gdu. They all have compiled arm static binaries.
https://dev.yorhel.nl/download/ncdu-2.3-linux-aarch64.tar.gz
https://github.com/dundee/gdu/releases/download/v5.27.0/gdu_android_arm64.tgz
adb push .\gdu_android_arm64 /data/local/tmp/
adb shell
chmod a+x /data/local/tmp/gdu_android_arm64
/data/local/tmp/gdu_android_arm64 /storage/emulated/0


text:
Trying to understand the options in TWRP backup
This is a screenshot of the twrp screen after you choose "Backup":

I have the following questions:

What is the difference between the options "Boot, System and Data" on one hand, and "System Image" on the other?
Is the "Data" option for data of system apps and user apps, or only system apps?
I want to take a backup so that I can get a file that I can flash with Odin (that is, without requiring twrp). Which option should I use?
What is "Vendor Image", and how does it differ from "System Image"?
What is the difference between "Vendor" and "Vendor Image"?

These are all partition names, see details here: https://forum.xda-developers.com/android/general/info-android-device-partitions-basic-t3586565

@IrfanLatif That link mentions the partitions, but my questions #1, #2, #3 and #5 remain unanswered.

Image is dd backup i.e. the exact copy of whole partition (to retain Verified Boot), the other one is tar backup i.e. the contents of filesystem. I don't think restoring TWRP backup through odin would be possible but I never used Samsung device. May be the Images can be restored. All of the remaining questions are answered once you know what these partitions contain.

as Irfan pointed out in his comment, "Image" means creating a partition image (using dd). Normally, TWRP creates tar archives with all the files located on a given partition, which then is much smaller.
"Data" contains all data – i.e. data & configuration from system apps as well as user apps. As the /system partition is mounted read-only during normal operation, that's where all "variable data" go (apart from files you store to the SD card).
Probably none of those. It's unlikely Odin understands any of the TWRP backups (you can try, and I stand corrected if you find out it can – but no guarantees from my side, including that it doesn't "brick" your device – I'm not a Samsung user)
Vendor is stuff very specific to your device provided by the "vendor", i.e. usually the manufacturer (including customizations) – while System is the "Android base" (though this separation is rarely absolute)
Same as between "System" and "System Image" (see 1.)


text:
Are printer drivers technically possible?
It seems that printer manufacturers like Canon provide a printing app for Android devices, from which you can print documents and images stored on your Android device, but not printer drivers. So you cannot just print from any app, in the way that you can print from any program on a computer with printer drivers installed.
Is there a technical reason why there are no regular printer drivers for Android devices? Or is it just a choice made by manufacturers?

Is HP Print Service Plugin considered as a "printer driver" in your context? That aside, printing is only available natively since Android 4.4 KitKat and needs to be implemented by each individual app.

@AndrewT. That indeed seems to have regular printer driver functionality. They even call it a printer driver. And if an app doesn't support the "print" option, you can use "share", which is a logical way of doing this generically on Android, I guess. I wonder why not every printer manufacturer followed HP's example on this.


text:
unable to go into fastboot on LG phone
I have been told that LG phones are painful to get into fastboot but i didn't realize it was impossible. I have the LG K8 2017 (LG-M200n) and I have tried all: #adb devices shows the device is listed, then #adb reboot bootloader does nothing but reboot my usb connected phone. of course fastboot devices shows nothing. I even tried the recommendations to enter fastboot by power down phone, vol down key and connect usb, but phone turns on normal, no fastboot. any help?

can you enter any other mode? https://www.hardreset.info/devices/lg/lg-k8-2017-m200n/download-mode

yes download mode i can enter into it ok. I found the answer please see below. sad.

check fastboot devices in download mode

I found the answer. It is not possible because of the hardware itself. LG sucks really. Here is the info from their developers site which explains all the difficulty (LG K8 not listed below :():
"The following devices support unlocking the bootloader:
• LG V50: LMV500EM for the European market
• LG V40: LMV405EBW for the European market
• LG G7: LMG710EM for the European market
• LG V30: H930 and H930G for the European market
• LG G6: US997.USA for the U.S. open market
• LG G6: H870 for the European market
• LG V20: US996.USA for the U.S. open market
• LG V10: H960A for the European market and Android M (Except France)
• LG G5 SE: H840 for the European market
• LG G5: RS988.USA for the U.S. open market
• LG G5: H850 for the European market
• LG G4: H815 for the European market
Unlocking the Bootloader is only supported on selected devices."

The lesson learned here: verify the capabilities of the phone you want to buy before wasting your money.

https://youtu.be/3ExyUX4AC6w

nope. this is not a verified method. no links or guarantees. plus I am wary when a product is asking for $ without proofs. my answer above is still valid (unfortunately)

i don't want you to buy $ 399 https://octoplusbox.com it is for professional use only. but it is possible (not for consumers, at least). consider paying ~ 20 bucks for a unlock service, sure you will find someone who can do it


text:
Pattern Lock Nokia 7.1 even thought i gave correct pass code
i am using Nokia 7.1 mobile phone. i have setup screen lock pattern and finger  print.
Now, i have problem with the phone like not able to unlock the phone eventhought i am giving correct pass code and finger print.
Now i don't know how to fix this issue in Nokia 7.1 phone, please suggest he to fix the issue. I have been restarted multiple time and i dont want to do factory reset.
Thanks in advance.

Boot in safe mode. Delete all your fingerprints. Add one fingerprint. Add again the same fingerprint. If it says it is the same finger, then the reader is working https://community.phones.nokia.com/discussion/5841/fingerprint-scanner-not-working

Lock your phone. Set a temporary password to lock your screen. Unlock your phone with temporary password
https://myaccount.google.com/find-your-phone


text:
EXT4 Mount gives this error "SELinux: mount invalid. Same superblock, different security settings"
I am trying to mount a second partition  (ext4 ) for my apps ( I guess its a bit outdated with adoptable storage but then ext4 isn't accepted FS for adoption for external card ) . I am on 9.0 ( Pie ) and all my SD partitions are mounted under /storage and some weird name .e.g.
/storage/ 6226b27a-ebc1-4fdd-b54c-096abc40c2b9

Now I need my 2nd Partition to be mounted under /data/sdext2 but O.S already mounts it.
app2sd ( link2sd) gives me Mount script argument invalid argument . No matter what .
On digging further through OS logs I get this info
[   48.820728] EXT4-fs (mmcblk1p2): mounted filesystem with ordered data mode. Opts: nomblk_io_submit,errors=remount-ro
[   48.941276] EXT4-fs (mmcblk1p2): mounted filesystem with ordered data mode. Opts:
[   48.969786] sdcardfs: mounted on top of /mnt/media_rw/6226b27a-ebc1-4fdd-b54c-096abc40c2b9 type ext4
[   48.970918] Remount options were mask=18,gid=9997 for vfsmnt ffffffda2f7539e0.
[   48.971668] Remount options were mask=18,gid=9997 for vfsmnt ffffffda95617660.

......
[  107.476736] SELinux: mount invalid.  Same superblock, different security settings for (dev mmcblk1p2, type ext4)

What I did :
Umount partition as mount master under Terminal Emulator. Its umounted only in context but not everywhere. But in-spite of umount I cant seem to mount it under /data/sdext2

Whats happening  and how to work around .

On a side note. How do I manually assign mount point names  and prevent these weird names given by OS to the partitions
and on a 'side side' note. I am not even sure if this is the reason for invalid mount error as I read elsewhere its more of a benign FYI message.

you can handle it two ways: 1) umount /dev/block/mmcblk1p2 (with busybox) before mounting /data/sdext2. or 2) bind mount /mnt/media_rw/6226b27a-ebc1-4fdd-b54c-096abc40c2b9 to /data/sdext2

Weird name is filesystem UUID, that's how Android uniquely identity external SD cards and USB drives. And as Portable Storage, external SD card is mounted under /mnt/media_rw/, apps just see it under /storage/ through Storage Access Framework (SAF). Nothing else I get from your question what you want to achieve.

[  107.476736] SELinux: mount invalid.  Same superblock, different security settings for (dev mmcblk1p2, type ext4)  this☝ error... why do i get it and what is the fix Thank You for responding

that was long time ago, i did some tweaking Which I can't remember now but i don't see it now. But not sure what caused.it


text:
Linking social media data to SD card - how does Samsung do this without partitioning the SD card?
I am using a Samsung Galaxy On7, Android 6.0.1. In the latest update (released April 2018), they have added a feature such that you can store your social media content on SD card, but link it to the internal storage. For example, Whatsapp still doesn't support reading the SD card. If you enable the "Move to SD card" option, the phone will move all Whatsapp data from internal storage to SD card, but these will still be accessible when you open Whatsapp.
I know about the Link2SD app, which creates a second partition on SD card and treats it like internal memory. But here there is no such partition created. How does Samsung make this link? Is there any app available that can do this same thing (the app may ask for superuser access, I have no problem with that).

i don't think it is a link (nor samsung feature) https://android.stackexchange.com/questions/155565

init.d outdated but you can still use the mke2fs command to create 4 GiB ext4 image and mount it to /data/sdext2
https://forum.xda-developers.com/android/development/tutorial-how-to-emulate-partition-sd-t3554949


text:
Android version stable version?
I do not use my android phone for anything but making phone calls and browsing the web not logged into anything.
Is there an Android phone version or phone that is not upgradable.  I have noticed as the phone upgrades on both my iPhone and Android the versions of the phone gets slower.
Maybe android go or android one?
The Google Pixel works because you can install any ROM but is slightly to expensive.

That's the first time I hear someone complain that there are updates. That's a novum. Unless you buy a flagship device, updates being available are rather exceptional. Well, and if you insist, you can ignore update announcements and simply not install them.

@Izzy that is exactly what I do my iPhone mjcro updates auto install on Android

Urgs, it shouldn't do that… But if it does, I've no idea how it could be prevented.

Oneplus are a decent solution.


text:
Android : how to remove the downloaded android update
I have a securities concern. I installed a VPN software on my android and just after (the next day) android asks me do install an update (that is already downloaded via the VPN). I don't fully trust my VPN software and I can not trust that the downloaded update is legitimate. I would like to force Android to redownload this update but from OUTSIDE the VPN (so delete the downloaded file and let android redownload it). How to do that?

It would help if you mention which Android device and Android version you are using. For some devices, clearing data and cache of system update app is sufficient, while for some pre-8.0 devices, the update might be located in the cache partition. Additionally, OTA updates in non-A/B devices are cryptographically verified by the recovery partition that the update is genuine (comes from the oem) so your fear might be unfounded. I don't know about such verification for a/b devices though.

@Firelord :  OTA updates in non-A/B devices are cryptographically verified by the recovery partition that the update is genuine (comes from the oem) so your fear might be unfounded ... are you really sure :(

Check "5." under "Life of an OTA" here: https://source.android.com/devices/tech/ota/nonab


text:
Printing photos off of Android phone with "Verifiable dates"?
How does one print photos from an Android phone with a date on it?
When the original photo doesn't show a date on the actual image?

I'm not sure what you mean by verifiable days, but dates are typically recorded as part of the filesystem when the photo is created. A date may also be embedded in the meta data if the image (EXIF data) and this is more reliable when recorded. Of-course, if the date is not correct in the camera when the photo is taken this info will be inaccurate. BTW, EXIF data can record a range of things, including location, camera settings etc. Actually printing the photo depends on the specific software being used.

You need to find an app which can take exif data out of images and edit the images automatically with the exif data to achieve what you want.


text:
Lineage OS 16, Nandroid Backup Not Working
I am currently running the April 29th build of LineageOS for MicroG 16.0 on my OnePlus 5 (cheeseburger). I tried to update the device using the built in Updater, but the device just rebooted into TWRP and showed the TWRP logo screen for some time. After that, I got this error message:
Checking for MODEM build time-stamp 2019-07-18 14:56:39
Error: This package requires firmware version 9.0.7 or newer.
Please upgrade firmware and retry!
Updater process ended with ERROR: 7
Error installing zip file '@/cache/recovery/block.map'
Done processing script file

After searching for a solution, I decided it would be best to just backup my data and reinstall Lineage.
After looking through my options, I decided a Nandroid backup through TWRP was my best option. So, I tried to take one. This was the result:
createTarFork() process ended with ERROR: 255
Backup Failed. Cleaning Backup Folder.

If I adb pull my recovery.log, this is where I get my errors:
E:tar_open error opening '/data/media/0/TWRP/BACKUPS/[serial_number]/2019-08-10--23-11-06_lineage_cheeseburger-userdebug_9_PQ2A190405/data.ext4.win000'
Error creating backup.
I:Error creating tar '/data/media/0/TWRP/BACKUPS/[serial_number]/2019-08-10--23-11-06_lineage_cheeseburger-userdebug_9_PQ2A190405/data.ext4.win000' for thread 0
Error creating backup.
I:ERROR tarList for thread ID 0
Error creating backup.
I:InfoManager saving '/data/media/0/TWRP/BACKUPS/[serial_number]/2019-08-10--23-11-06_lineage_cheeseburger-userdebug_9_PQ2A190405/data.info'
createTarFork() process ended with ERROR: 255

I read up about this type of error and found out that it means that those files have been corrupted and should be deleted. The strange thing is that the day before yesterday when I deleted the files in the /data/media/0/TWRP/BACKUPS/[serial_number]/ and then tried to perform the backup again, it regenerated files in the same directory, causing the same error. I also find it strange that the files that are causing the backup to fail seem to be backup files as well, although I've never performed a successful Nandroid backup on my device.
So, what can I do to fix this error and finally be able to backup and update my device?

Comments are not for extended discussion; this conversation has been moved to chat.

https://android.stackexchange.com/questions/214872/how-root-huawei-y7-trt-lx1-switch-slot/214897#comment275425_214897


text:
Can't find eSIM option on Google Pixel 3
According to specs, Google Pixel 3 supports eSIM, but under Settings > Mobile networks, there are no relevant options.
Is this depending on whether I'm currently in the service area of a mobile network operator supporting eSIM or should this option appear regardless? If so - why doesn't it appear?

Enabling developer mode made the option miraculously appear.


text:
How can I transfer android data to PC (windows) given that phone screen is not working and I don't want to replace it.?
I have a LeTV android phone launched in India in 2016, now the company has been shut down. Few days back, my mobile screen suddenly just went off. Now it is just switched ON. Before dismantling it, I want to transfer my data to my PC as I haven't set backup on. I tried through command prompt adb commands but it is saying  device in unauthorized, do it by clicking on screen which I can't do. Please help me, how can I transfer data.

Both of your queries are of most widely discussed topics. Make a search and you will get hundreds of answers like this and this.

First buy USB-OTG adapter and try to connect keyboard/mouse. If no USB-OTG support, you could flash rom with ro.adb.secure=0 and userdebug. or inject init.d script which will sync /data/misc/adb/adb_keys from any given location (cache, system, sdcard). For unencrypted Mediatek devices simply readback with SP Flash Tool

TWRP has adb shell, too https://twrp.me/faq/openrecoveryscript.html

ADB commands won't work if you haven't set up USB debugging prevoiusly, and also allowed your computer to debug the phone.
If I understand you correctly that your phone only turns on, but you cannot see anything on the screen, I am afraid nothing can be done. Take your phone to a person who can fit in another display. Otherwise, this seems virtually impossible.

OP stated that usb-debugging is on, just not able to confirm the RSA-Key


text:
Successfully installed TWRP and Magisk means bootloader unlocked?
I have a Samsung Galaxy On7, running stock firmware, Android 6.0.1. I have successfully installed TWRP and also flashed Magisk. In the developer options, I have toggled the "OEM Unlock" option to ON position.
I was reading that in order to flash a custom ROM like Lineage OS, I have to unlock the bootloader. There are a number of methods to check if the bootloader is unlocked, viz. one from fastboot and one by dialling certain commands in the phone dialer. Unfortunately, fastboot cannot recognise my device in Download mode, and the dialler commands are not working too.
I read somewhere that toggling the OEM Unlock option to ON means my bootloader is ulocked. Is that true? Having been able to successfully install TWRP and Magisk, can I conclude that my bootloader is unlocked?

Install Google's ADB drivers, connect your phone to your PC, open a command prompt and type:
adb reboot bootloader

Then:
fastboot oem device-info

And you will see the bootloader's status, either in the command prompt or on the device's screen.
To unlock a locked bootloader, type:
fastboot oem unlock

Remember that unlocking the bootloader will wipe all of your user data, as a factory reset does. Backup your data first.

Since you have a Samsung phone, remember that Fastboot isn't supported, while Odin is. To unlock the bootloader, simply find the OEM unlock entry in the device's settings and enable it.

In my question, I have stated, "Unfortunately, fastboot cannot recognise my device in Download mode, and the dialler commands are not working too."

ah, i forgot. For Samsung phones you dont have to unlock bootloader, it's enought to enable OEM unlock in developer options, and flash new ROM. Because samsung uses Odin instead of bootloader, it much harder to work with bootloader on samsung, and after all there is no need for that, everything will be fine. Just flash that custom ROM you want, from TWRP and you will be fine. Make a backup if anything goes wrong.

Please add the comment to your answer so that I may accept it. :-)

I edited your answer for clarity, if you don't mind.


text:
What is the fastest way to shutdown unrooted Android phone?
Sometimes I need to have my phone shut down as fast as possible. In older phones I was able to remove the battery, but after some "innovations" this feature is no longer present. Is there any better option than using casual shutdown and waiting for long seconds until it gets down? It is especially bad when I pour water on my phone and the touchscreen refuses to work.
I am using Xiaomo Pocophone F1 with Android 9.0.

Just to be clear, would a solution be acceptable which shutdown phone normally but without requiring touch input? (This would require root access though.) Power key can be setup to initiate that shutdown on long-press of X number of seconds. It is best if you mention the Android device and version you are using.

I would like to kill it instantly if possible. Long press of some key is usually too long to be considered "instant"

You are missing the point. If touch fails to work, only volume or power button can be depended upon. You can either configure them to shutdown the phone on just one touch or on long-press. If configured for a single press you would lose original functionality from those buttons, so the choice is yours to make for the trade off because the OS cannot know automatically (unless some sensor is built to do that) that water has entered into the device.

just for fun: set MacroDroid to execute reboot -p on shake sensor as trigger. if your phone gets wet, just smash it down, it will immediately shut off (combination of all suggestions)

In fact without removing battery it's not possible to shut down a device completely in order to avoid the loss that could possibly occur due to short circuit caused by water.
Let's have a brief look at what shut down means and what are possible options to achieve this.
HOW SHUTDOWN WORKS?
Android is based on Linux kernel which is the very first executable of operating system which is run during boot process. Kernel initializes necessary hardware and prepares a basic environment before executing init, the very first userspace process we can see. It's init which then starts and takes care of all services and processes. On shutdown, reverse of this happens.
INIT
When you tap Power Off from Power Menu, or when you issue reboot -p command from terminal app or adb, it sets Android property sys.powerctl to shutdown (with an optional reason for shutdown) which tells init it's time to save any unsaved work to persistent storage, stop all services and processes gracefully (or brutally), sync filesystem caches, un-mount filesystems and then hand over charge to kernel by making syscall reboot (ref). Kernel then makes sure all userspace processes are stopped including init, forcibly unmounts any stubborn filesystems and ultimately powers down hardware devices including CPUs and RAM.
Android's init supports two modes: shutdown and reboot. Linux init has some more shutdown options including halt and poweroff. See this answer for more details.
KERNEL
Most of the time during shut down is taken by init. In order to save time you can bypass init and ask kernel directly for a poweroff by making syscall:
reboot(LINUX_REBOOT_MAGIC1, LINUX_REBOOT_MAGIC2, LINUX_REBOOT_CMD_POWER_OFF)

That's what busybox poweroff -f command or the magic SysRq key O (equivalent to Alt-SysRq-O on a PC) would do (ref).  Both should be preceded by sync to avoid damaging filesystems. From commandline we can do:
~# echo 1 >/proc/sys/kernel/sysrq
~# echo s >/proc/sysrq-trigger
~# echo o >/proc/sysrq-trigger

This is the fastest way to shutdown OS on rooted device.
HARD REBOOT
But how to power down the device if even the kernel becomes non-responsive? Hardware can usually take care of this i.e. if you keep power button pressed for a fixed time interval. There's some hard-coded value (mostly 10 seconds) inside Power Management Unit (PMIC). No process will be stopped, no filesystem would be unmounted, no goodbye would be conveyed, just the power will be cut to CPU, RAM and other relevant hardware resources. Most SoCs (which have PMIC embedded inside) implement this as reboot, not shut down.

So to summarize the above lines, there are two ways to shutdown device: through init or calling kernel directly. Both can be achieved through simple shell commands or can be mapped to some hardware key or special key combination. But water can make any hardware key useless, so this method can't be a universal solution.

POWER BUTTON
But the point is, your device isn't fully powered off whichever path you have chosen. During boot process there are things which are powered up before the OS loads (and possibly be powered up even when there is no OS on device). There must be a circuitry in PMIC (e.g. a microcontroller in low-power mode and may be some software stack too) which is always powered up so than it can listen to your request for switching on the device when you press power button for a few seconds, or even when you connect a charger to device in powered-off state.
COMMUNICATION PROCESSOR
Also the baseband processor (BP) - which runs modem and is responsible for all communication through mobile networks e.g. call, SMS and internet - is totally isolated from Application Processor (the one we call CPU) and is not governed by Android kernel; it runs an independent RTOS. And as they say, government agencies may use it to track you even when you think your device is powered off. So it means it may possibly be (partially or fully or periodically) running when Android isn't running.

If nothing else, at least battery terminals are always live, connected to some part of motherboard which may get short when got wet. So if your device isn't water resistant and the battery doesn't have some short-circuit protection built-in, you can never be dead sure your device won't get damaged when water poured on it.

Thx! i watched all episodes of Mr. Robot but i didn't learn that NSA can hack baseband processor even when phone switched off! :) Now we know the reason for this "innovation" of non-removable batteries!

@alecxs baseband processors are one of overly closed-source products. Don't know what the dominant factor is. If the giants like Qualcomm are keeping backdoors or hiding their security vulnerabilities or don't want to put users' privacy at stake.

You can shut down your device by holding

Volume Up + Power Button

simultaneously for several seconds.

If you continue to press the power key, it will shut down without confirmation. That takes yet a few more seconds but doesn't require the touchscreen in the event you've described.
p.s. Going on a tangent, I find that locking my screen and wiping it often works if a bit of water messes with the touch screen. But if it's drenched shutting it down would be better for the electronics.

In my case it reboots the phone


text:
How safe is it to build and flash LineageOS myself?
I was planning to flash LineageOS on my Asus Zenfone 2 Laser, but I recently found out it is no longer supported on my phone. However, this guide explains how to build then flash the ROM on my device (and possibly root it), and I truly want to go down this path.
What is unclear to me a this point is whether it is "safe" to do so. More specifically:

Will I be getting security updates ?
Will it be safe to use banking apps with the custom ROM ?
What can happen if I lose/someone steals my phone ?
Should I stick with my bloated stock ROM ?

Thank you in advance for your help !

Does your bloated stock ROM get regular security updates? Is it safe to use banking apps on it? I would argue that this can only be determined per device, since some devices lose support from their manufacturers quicker than others due to popularity in sales.

@LucasRamage Perhaps you're right. On mine, the "About" section indicates "Android security patch level : feb 5 2018" (or something like that, because it's in French). Does this look reasonably recent to you?

That's better than many for sure.

Will I be getting security updates ?

LOS team will keep merging in Android-side security patches, so each time you sync and build you get the latest they've merged, but kernel-side ones are up to you.

Will it be safe to use banking apps with the custom ROM ?

Root is optional on LOS - if you don't opt into that, the risk is low.

What can happen if I lose/someone steals my phone ?

With encrypted data and a good enough lockscreen passcode, your data will be secure.

Should I stick with my bloated stock ROM ?

Why did you ask this question in the first place? ;)

BTW, if you just want to get any LineageOS build or even any custom ROM, check here for older LOS builds, and XDA for more stuff.

I think it should be noted that to receive the LOS patches, OP will have to update their source, rebuild and flash the updated system. They won't be available OTA

@AndyYan Thank you for your quick response !
Supposing that I root while flashing, do I have to be as careful as with any other rooted phone ? (I'm thinking of using automation for advanced customization)

@Namnodorel Done.

@mEEGal It's rooted, no different. Handle carefully.


text:
OnePlus 6T Did "fastboot boot" just delete all my encrypted data?
Today after a successful(Booted, worked fine all day) OTA manual upgrade(downloaded latest zip and flashed) I decided to reinstall TWRP in order to reroot. However, after running first "fastboot flash recovery twrp.img" then "fastboot boot twrp.img", I am no longer prompted to enter my passcode(which I know) to decrypt the device, and the /system partition is empty in the TWRP file manager. The sdcard partition is filled with my encrypted files(assuming by their base64 names).
I dont think any of my actions in TWRP were significant, except possibly when I flashed the twrp.img to have the recovery be persistent. (When I launched TWRP for the first time, I wasn't prompted for my password to decrypt then either, so I assume the damage was already done)
I have tried "twrp decrypt [password]" in the twrp terminal but I get "Failed to decrypt data".
When I try boot into system, I either bootloop or TWRP launches instead.
A. Is there a way to reflash my system(e.g Can I just flash the same update.zip) and be back to normal
Or B. Can I retrieve and decrypt my data, given that I know my lockscreen passcode which is normally used to decrypt it.
Here is everything I wrote in my command prompt
Here is ls -la /

this devices does not have a recovery partition. therefore you probably need to flash back stock boot.img, then boot into twrp and install twrp from twrp

@alecxs Just to be sure, I flash the same whole stock image(https://www.oneplus.com/uk/support/softwareupgrade/details?code=9) as it was before, or flash only a stock recovery image from someplace online?

extract the boot.img from stock rom and download twrp-3.2.3-2-fajita.img. flash boot.img to boot and boot twrp.img from fastboot. then install twrp-installer-fajita-3.2.3-2.zip from twrp. please read the instructions https://twrp.me/oneplus/oneplus6t.html

@alecxs I cant thank you enough! Almost had to write a new CV

Full credit to alecxs for this answer. Posting incase anybody else has the same problem in the future.

Download stock image(Mine was oneplus.com/uk/support/softwareupgrade/details?code=9)
Use extract_android_ota_payload-master to split the payload.bin inside the zip
(Method for step 2 https://pastebin.com/RfEHuvu7 , I did this on linux because my linux machine has python2 installed, no other reason)
Flash the boot.img and boot with twrp
(Step 3 https://pastebin.com/Gp9aJq36)


text:
Storage setting not loading. What do do?
When looking on the storage option it just loads forever, and can't view the setting option. What do I do?
I have a Moto E.

What works for me is first going to Settings >  Apps & notifications, and clearing the cache for as many apps as I can.

I have found a solution to this problem. Just put your 'Sleep' functionality to 'After 10 minutes of inactivity' and then open storage.
It will take approx 6 to 7 minutes to open. Once opened it will work fine.
With Regards,
Asif


text:
Changing Mac Address on Mi A1 running LineageOS - where to look to fix problem?
I have a rooted Mi A1, and upgraded to the latest LineageOS daily build (Pie). Most things work OK, however I can no longer change the MAC address of my device (which worked on stock). I'm trying to work out if this is something I can hack/fix.
I have downloaded a couple of programs to change the MAC address, and have also tried in an ADB shell.  What I noticed is that when the MAC address changes  the connection appears to go down, and then when it comes back up its reset to the original MAC address.
The driver appears to be wcnss_wlan and the chipset on the phone is, I think, MSM8960 (but could be wrong here).
When I manually try and bring the interface up at the command prompt using ip link set dev wlan up, it does not work (I can bring it down OK, and can change the MAC OK using ip link set dev wlan0 address ma:ac:ad:dr:es:ss ), and when I use the toggle on the phone the interface gets reset to its default MAC.
Can anyone advise a way to fix this, or point me (even vaguely) in a productive direction - ie where can I find where the MAC address is coded, how to I manually trigger a DHCP update?  How do I look at whats happening with WPA_SUPPLICANT ?

Why did you installed LineageOS in a Android One device?, I guess it's for fun. Anyways, my experience with custom roms and daily builds is that nothing should be expected to work, so don't waste your time trying to solve something broken.

@JoseAntonioNavarroMarco I installed LineageOS because Android was not getting updates under stock as I have rooted it and as such there are significant vulnerabilities on a device which holds keys to other systems (and also the phone is 2 years old). I really did not want to update, but I'm glad I did. LineageOS/Pie is more polished.  Importantly I disagree with your philosophy about not solving problems in daily builds - its part and parcel of open source.

I'm an android developer myself and I can assure you daily builds are far from being released, far from being stable, and far from a smooth experience. Anyways, if you still want to solve this problem, ask in lineageOS forums, contact the developers directly, maybe they can help you, they are the only ones that know how does something done yesterday works.


text:
How do I get rid of "the connected device is unable to access data" notification
When I connect my phone to my job computer the phone shows a "the connected device is unable to access data" dialog from time to time. I think this is just annoying - if I want to access files from my computer I would notice that when I try and if I don't I couldn't care less.
Is there a way to disable that popup from appearing? I'm using a Galaxy Note 9 (in case that make any difference).


text:
Huawei Y9 Pro camera issues
I've recently got a Huawei Y9 prime and I hope it will have good quality in videos. But unexpectedly there are not very clear as I expected. I mean all of the videos have a wave-like effect on it. Is it a problem with the camera?
Any idea how to fix it?

Dude, it's because of more added grain and smoothing the grain making it look like low textured pic, but if you want to know a temporary fix then download Adobe light room to take pics and edit them just by pressing auto(in the edit menu) and then going to effects or details to increase the texture as per your liking.
I also have a huawei y9 prime 2019 and wasn't expecting that, but by some research (a lot) I was able to get a news that it will be with the help of some upcoming updates...
So we gotta wait until then.
Hope the temporary solution helps


text:
Is it possible to use a Bluetooth earpiece while using a microphone plugged into the headphone Jack?
I'm going to be attending an event as a representative of a semi-professional podcast.
I will be interviewing several people but, it is a long, busy event with no area for formal interviews, so I will be using my phone (Samsung Galaxy Note 9) with an external microphone to save space.
In discussion with the podcast host it was suggested that we try to set up a "live feed" so that he can give any input during the interview.
The "live feed" isn't too much of an issue as I am capable of streaming content from my phone.
My main concern is being able to hear him over the crowd, usually a Bluetooth earpiece would solve this.
However, I'm not sure if an external microphone plugged into the headphone Jack port would override the earpiece as the microphone.
Does anyone have any experience using both a Bluetooth earpiece and a Jack microphone simultaneously?
If nobody has tried this before, is it even theoretically possible?

After a fair amount of testing on my Samsung Galaxy Note 9, using server different apps, I have discovered that it is not possible to use a 3.5mm jack microphone in conjunction with Bluetooth headphones.
Instead I had to use a 3.5mm splitter cable (widely available online) and connect my microphone and regular 3.5mm jack headphones.


text:
Recovery approach for lost partition and encrypted F2FS
The Problem and Mystery
My ZTE Axon 7 [Android 7] inexplicably wiped its emulated storage area /storage/emulated/0 while retaining all installed applications, albeit with settings wiped clean. There was also a 256GB sd-card mounted as a add-on, system space. I think it was configured as F2FS and encrypted. I've stopped using it and bought a new phone. I want to image the phone's internal memory and the sd-card, and recover what I can that wasn't backed up. I don't know the best approach, but know there are some hurdles, which I'm unsure how to approach.

What is the best way to image phone memory? Recovery mode and ADB?

The F2FS and internal memory may have been re-partitioned and/or reformatted
Getting the image would allow me to scan for text, strings, and file signatures

Where is the encryption key normally kept? Is it backed up anywhere?

The original file systems are likely encrypted, and would need a key
I know the phone would store this somewhere, but unsure how to retrieve it.
Key may have been overwritten or reset, since I didn't immediately realize something happenend, plus don't fully comprehend what did.

Is there any way to view the contents of a GDrive backup? Any chance it contains key?

There is some backup data on Google Drive, but haven't viewed yet
This backup may also have been overwritten, since I see no versioning info
Backup data is not very large. Maybe a few megabytes.

How did this happen? Does my story below add up?

I'm hoping there's an alternative cause and fix to this

How it happened
Not sure since I was using Android Auto for navigation and music, and the phone was normal. At some point the phone became "weird" with the wrong launcher, which I ascribed to accidentally pressing a wrong button and activating another launcher (I had several installed), and I switched to my wife's phone. Later I realized every app was "weird" and then checked the FS and realized everything, photos, docs, were missing even at the file system level.
Maybe I pushed a system upgrade prompt, or confirmed some other crazy phone action. I was driving and don't know.

i am afraid you can do nothing to recover phone because you did not unlock the bootloader. it may caused by f2fs itself (it is buggy) https://forum.xda-developers.com/axon-7/development/recovery-official-twrp-zte-axon-7-t3515715

https://forum.xda-developers.com/general/rooting-roms/how-to-backup-qualcomm-phone-root-t3570178

I'm pretty sure I can unlock the bootloader now, but not sure if it will help

don't do it now, it is too late. find a exploit for booting twrp without unlocking bootloader. maybe there is some way with Qualcomm HS-USB QDLoader 9008 Driver and QPST

@alexcxs, since my Axon is now an extra phone, after giving up on this data, should I root it anyhow? Root and sell, or just sell? Thanks

Yes, but I thought you just said "you can do nothing to recover phone because you did not unlock the bootloader. it may caused by f2fs itself". Is there a chance to image the data and try to recover something? - Sorry, just saw your updated comment. Will try the Qualcomm driver

try the second link to get a dump of your phone with HDDRawCopy. then we will see if the key is recoverable from /data/misc/vold this would help to decrypt sdcard. there is a exploit to get the Keymasters Key blob (which may help to recover data from phone dump) but this requires highly expert skills https://www.theregister.co.uk/2016/07/01/turns_out_breaking_android_fulldisk_encryption_is_easy_with_the_right_code

Possible duplicate of How to recover a deleted file from /data partition?


text:
what versions of android lets you share saved wifi using qr code?
i am trying to list the versions that support sharing saved wifi through qr code .

This is a feature of the upcoming Android Q version.
There are device manufacturers who have already implemented this feature in their current Android 9 devices (e.g. Huawei).

can i get a refer ?

I have not found an official announcement by Google, but if you search for android wifi qr share you are getting plenty of sources from news sites. The fact that Huawei already has this feature I got from a German print news magazine.

I searched that but all what I found was apps .. I asked some people and have found that is there on these models Huawei Y7 Prime android 8
xiaomi note 6 android 8 / 8.1
Xiaomi Mi 9 android 9
Xiaomi Note5    8 / 8.1            and many more I think . where do you think I can get more info ... And there is another question on xiaomi you have to be currently connected to that network to be able to share the qr code .. And you can't do it on just  saved WiFi networks .

Just use one of the following articles: Q 1 Q 2 Q 3 Samsung

Yup ... the other phones brands that doesn't have android Q added it based on the manufacture UI .


text:
recovery of data on MMC protected internal memory device
I have a broken HTC Sensation with a forensics lab who are trying to recover the data from the phone's internal memory chip. The technician says he is unable to recover the data on the chip because the chip itself is MMC password protected. This is the first time he has ever encountered this on an internal memory chip. He added that he was mystified as to how an internal memory chip could become MMC password protected in the first place.
I should add that this phone belongs to me. It is not nor was it ever password protected.
Can anyone here offer any guidance on solving this problem? I simply refuse to believe that HTC have for the first time in the history of civilisation, created a perfect security measure and then installed it into a mid-price mobile phone handset.
Many thanks

https://bits-please.blogspot.com/2016/06/extracting-qualcomms-keymaster-keys.html for older devices: https://www.forensicswiki.org/wiki/How_To_Decrypt_Android_Full_Disk_Encryption#Locating_the_Encryption_Key

I'm not sure what he means by password protected but yes, most of the newer Android devices are encrypted with default_password on first use. So even if user doesn't enter a password on boot, memory is encrypted (FDE/FBE). Memory is encrypted with a key which is stored in footer of partition, key is in turn encrypted with default_password (or user provided password). Additionally starting with Android 5.0 encryption is hardware-backed. So an off-the-device decryption is almost impossible.

its an old device check the version major/minor crypto footer - if it is < 1.3 it is possible to bruteforce https://nelenkov.blogspot.com/2014/10/revisiting-android-disk-encryption.html here is the script https://santoku-linux.com/howto/mobile-forensics/how-to-brute-force-android-encryption/#run-brute-force

Okay, I've found a little more information as follows: the chip is a standard BGA 162 SKHynix(?) chip with no unusual markings. The technician who is dealing with my phone went on to write: Due to the age of the device there won't be any FDE on it.
We basically have a hardware based lock within the memory chip itself, a fault we cannot overcome (without a special "Erase" command - as the name suggests this would wipe the data). I am struggling to think why this chip has an MMC lock but when I researched it, there tends to only be a small number of phones and chips out there with this issue.

thanks for clarifying this is a hardware issue (not related to encryption)


text:
Settings crashes when I try to set a screen lock
I have a Google Pixel. The bootloader is unlocked, but the system software remains unmodified.
A few days ago, I booted into TWRP (flashboot boot twrp.img) to access the data partition. The encryption key for the data partition is encrypted with a key that is partly derived from the unlock code. I was under the impression that touchscreen input with TWRP would be very mininal due to it being a minimal recovery system, so I had figured that I would not be able to enter my password so TWRP could then mount the data partition. I search the internet for this question and the results said to remove the lock screen password. I did that and I was able to access the data partition while booted into TWRP.
I rebooted my phone into normal Android and I successfully set my lock screen password again, BUT I may be misremembering this and it may have been that I had unset my password, then set it back up, and THEN booted into TWRP for the first time. The problem now is that when I either:

Go into Settings and select Security & location > Screen lock
Press the box at the top of the main menu in Settings that says "Secure your phone"

Settings crashes. Now I cannot set a screen lock. Why is this happening and how do I fix this?
These are not solutions:

Wiping my phone.
Restoring from a backup.
Anything to do with syncing with Google.

If you have Android 8+ you can change the lock screen via adb: https://www.theandroidsoul.com/change-remove-lockscreen-pattern-pin-password-adb-android-oreo/

@Robert Sounds too risky. I think I might lose the key that is used to decrypt my data if I do that.


text:
How to copy / modify data from a soft-bootlooping Samsung Galaxy S2 (GT-I9100)
The Samsung Galaxy S2 (GT-I9100) I have at hand was turned off after getting hot during standby. When trying to start it again, it was in a bootloop: Like usual, it first shows "Samsung Galaxy S2 GT-I9100", then shows the provider branding and then shows "Samsung". But at the time when it was normally asking for the PIN, it was again showing the provider branding and going into a loop.
It is possible to go into the recovery mode. Among other things (see below) it shows "E:Error in /data/log/recovery_log.txt (No space left on device)".
The phone was running the newest stock firmware (Android 4.1.2). (At least I’m quite sure it was the newest version.)
Is there something I could try to make it start again, without loosing any data? For example, it could be the case that it’s not starting because the /data partition is full. Is it possible to remove files from this partition when booting the device is not possible?
If that’s not possible, is it possible to backup all the data (including app data and the internal "USB" storage), without loosing any data?
It seems like installing a different recovery ROM makes it possible to backup the data. However, I’ve read that installing a different recovery on a S2 with a stock ROM will stop the system from booting. In this case it doesn’t boot anyway. But in case it’s possible to fix the problem by making space free on the /data partition, can the original system be restored?
Some things which I observed that may (or may not) be helpful:
The recovery mode says "Android system recovery <3e>" at the top and "# MANUAL MODE #", "-- Appling Multi-CSC...", "Applied the CSC-code : DTM", and "Successfully applied multi-CDC" in the middle, right over the out-of-space error described above.
When turning on the phone, the provider sends SMSs to everyone who has tried to call the number while the phone was off. Even though the phone is boot-looping, such notification was sent.

@alecxs If I understand correctly, the "internal memory" consists of two parts: a system part and a USB-accessible part. Will any of these be included in the backup? Which part contains the app data (I’m particularly interested in the backup of the WhatsApp messages)? It seems like I can restore the original system by flashing the original ROM. Is there a reliable way to find out which image I need? Are there any precautions to make sure I use the correct ROM and don’t override the data?

https://forum.xda-developers.com/showthread.php?t=3740526

@alecxs The TWRP instructions in the link say that IsoRec has to to be flashed first. Does this work without deleting app and user data from the device?

you are right! seems installing twrp is not as easy as expected. try PhilZ-cwm it has -signed.zip which can flashed directly via stock recovery (mediafire/mega.nz links are working) https://forum.xda-developers.com/galaxy-s2/development-derivatives/philz-cwm6-stock-kernel-cwm6-root-exfat-t1877270

When a phone is constantly crashing without any changes from your side, getting hot, usually it has a more seriously reason. You should focus on how to get your data off the phone first.
The SMS availability notifications indicates that android is still booting, just the gui system_server is crashing. To avoid availability toggle Airplane Mode or remove SIM Card.
Your internal memory (mmcblk0) is probably near wear-out. This means it will switch from read-write access to a read-only mode (for some partitions or completely) and one day it becomes unreadable. So how is data stored? List of partitions
EFS        /dev/block/mmcblk0p1
SBL1       /dev/block/mmcblk0p2
SBL2       /dev/block/mmcblk0p3
PARAM      /dev/block/mmcblk0p4
KERNEL     /dev/block/mmcblk0p5
RECOVERY   /dev/block/mmcblk0p6
CACHE      /dev/block/mmcblk0p7
MODEM      /dev/block/mmcblk0p8
FACTORYFS  /dev/block/mmcblk0p9
DATAFS     /dev/block/mmcblk0p10
UMS        /dev/block/mmcblk0p11
HIDDEN     /dev/block/mmcblk0p12

Typical important partitions on most android devices are BOOT RECOVERY CACHE SYSTEM USERDATA.
The BOOT (mmcblk0p5) partition contains the kernel and rootfs for the OS. It then loads the ROM from SYSTEM (mmcblk0p9). both partitions are read-only and can be downloaded everywhere (stock ROM). RECOVERY (mmcblk0p6) is a separate emergency rootfs. Samsung like to make things complicated, so in your case it is a recovery ramdisk which is included in boot. CACHE (mmcblk0p7) is a writeable partition for temporary files during OTA updates and log files. It can safely wiped/formatted any time. USERDATA (mmcblk0p10) is the only writeable partition for apps data, user installed apps and user files. However, seems like your phone has another additional writeable partition UMS (mmcblk0p11) especially for pictures and downloads (in newer android it is merged aka emulated storage), this is what you call USB Storage.
In android you only have access to pictures and downloads. the apps data is protected from user access and can only be backup with root access.
Modern android partitions are protected from altering, you can not flash modified content with a locked bootloader. Unlocking bootloader will trigger a factory reset, this is for security reasons to protect your data from unwanted access.
Luckily this is not the case for your device, the GT-I9100 comes from stock with unlocked bootloader!
The Android system recovery <3e> (stock recovery) gives you a very limited emergency access (sometimes with backup user data / restore user data) and wipe data/factory reset and wipe cache partition and apply update functionality.
So how to get access to your data? You can flash a custom recovery like TWRP from flash tool. This will not alter USERDATA or UMS partition.
Even more lucky, someone has leaked the Samsungs internal-only OEM signing key for OTA packages! (for older devices only)
PhilZ Touch Recovery CWM 6 comes as flashable signed zip which can be flashed directy from stock recovery.

download philz_touch_6.48.4-i9100-signed.zip
copy file to MicroSD Card
boot in Android system recovery <3e>
apply update from sdcard

This will (hopefully) bring you to custom recovery (if not, reboot to recovery mode). Now you can backup your /data and /sdcard -> to /external_sd
Once the backup is finished, perform a factory reset to see if this fixes your boot loop. factory reset will only wipe cache + userdata your stock ROM remains intact. If the phone is working, restore your backup and use adb shell in recovery mode to examine/delete your files.
If you managed to restore your phone, get off all your pictures via USB. consider a cloud backup of WhatsApp and other apps in google drive. This will help you to migrate your data to another phone before old phone dies.

Thank you for your detailed answer! I tried to apply the "update", but it fails with This package is for 'galaxys2,i9100,GT-I9100,GT-I9100M,GT-I9100P,GT-I9100T,SC-02C' devices; this is a ''. I could modify the updater script, but then I need to sign the update. Do you know how this is possible?

Unfortunately, I can’t connect via USB (I tried different modes, but my Linux kernel shows errors when plugging in the cable). Maybe the USB port is loose. Is there an alternative?

https://www.aliexpress.com/item/32837765368.html

idk how to sign but the OP states it was done by chainfire. this is a temporary PhilZ-cwm (it does not flash recovery) it will only boot into PhilZ-cwm without modifying anything, maybe this one works https://forum.xda-developers.com/galaxy-s2/development-derivatives/15-11-2012-philz-touch-3-00-cwm-based-t1840223 also it mention Aroma File Manager you could try inside recovery (use v1.8)

It seems like only the data pins are not fully working. I was able to apply PhilZ-cwm6-XWMS3-FOP-5.15.9-signed.zip. I backuped /data and system, but I didn’t yet find out how to backup /sdcard (internal "USB storage") unfortunately.

Aroma File Manager has a terminal emulator, there you can mount /dev/block/mmcblk0p11 and copy files

I’m a bit confused between /emmc, /sdcard and /sd-ext. Anyway, I used Aroma File Manager for copying /emmc to the external SD card (which was mounted at /sdcard). Now I have everything backed up.

After deleting 1.1GB in /data/log, it even boots again! Thank you for your help!

https://android.stackexchange.com/questions/59979


text:
Using a PC or laptop to send keystrokes to type on Android
I wanted to ask if there is a way to use my computer's keyboard to type on my phone while it is plugged into the PC to charge. I was wondering if anyone on here has a setup like this.
The end result needs to be: I can connect my phone through a dock or some other USB cable and either switch between Windows on my PC to type on the Android device or find an OTG device capable of charging and connecting a keyboard at the same time. This wouldn't be ideal due to limited desktop space.
I could connect a separate keyboard with an OTG cable, but this would stop me from charging it while using it.
I could also use AutoHotkey or something similar to send keystrokes to the Android device over USB, but I'm not sure how this would affect charging it or transferring files over USB as well. It could probably be done but I don't know where to start.
Ideally, this would be the option I'd use.

The scrcpy program can both display the screen as well as send mouse and keyboard strokes to the USB connected Android device. I don't know about its Windows version, but Linux version works well

You can use a remote desktop application like TeamViewer for this. Download the TeamViewer apps on your PC and phone, and connect the phone to the PC. You can put your phone on a wall charger as well, because this method only requires you to have a working Internet connection on your phone and PC.

Note that TeamViewer has problems with a lot of non-ASCII characters, therefore for entering text it may be not the best choice. Anyway you can simply use the adb  shell for doing so: in an open adb shell just execute the following command: input text 'your text'. With a bit of scripting knowledge you could build a terminal that sends all typed text to the device.

+1 [scrcpy] works well on windows/linux with adb over network (i use it for FireTV). bluetooth keyboard is another wireless solution. i have seen samsung tablets charging and usb-otg at the same time (but most devices don't support this) https://www.amazon.com/dp/B07JZND95Z

Use scrcpy.

Free.
Fast, no lag.
If you use autohotkey, you can now use it on android. This is a big one for me since I'm used to typing with autohotkey shortcuts.
Drag and drop files to transfer. eg. find the file via "new/recent files" and attach and send whatsapp/signal. This means you don't have to open whatsapp/signal on your PC!
It works perfectly together with usb thethering or mobile hotspot.

Github page - Genymobile/scrcpy: Display and control your Android device

Just to note, you'll also need Developer options activated for scrcpy and adb to work... https://wccftech.com/how-to/how-to-enable-developer-options-on-android-11/


text:
cd into the external sd-card directory using adb shell
I have a Samsung Galaxy Tab 2 (actually, many of them) and I need to regularly push some files inside the external physically removable SD card of my tablets.
Android handles internal and external storage as follows:
/storage
  ├ emulated/0/ /* this is the internal storage partition */
  └ 9102-ABF4 /* this is the external removable SD card partition */

I thought I could find this path by browsing to the folder which is not named /emulated inside /storage since the other one is the one I want.
I want, using device's shell through adb, to navigate to (using command cd) a directory that I don't know the path of (9102-ABF4 written above, located inside /storage/)

what is your question? cd /storage/????-?????

@alecxs I want, using device's shell through adb, go (using command cd) inside a directory that I don't know (9102-ABF4 written above, located inside /storage)

@puffo The command alecxs presented to you does exactly what you want to do: cd into a directory the name you don't know (but you know the pattern of the directory name). Just try it out.

@alecxs You should make an answer from your comment. Using wildcards with cd is a nice trick especially as it should work perfectly for all sd-cards as the pattern is always the same.

@Robert i am afraid the question is off-topic so i won't answer - besides this it's not worth it because that are basics in shell coding ;)

If your Android is 6 or above, and if your are connected through USB cable and your Android have USB debugging enabled, and if you have installed:
sudo apt install adb perl

put in a Linux terminal:
adb shell sm list-volumes public | perl -lane 'print $F[-1]')

This will show the micro SD card identification, example:
9102-ABF4
I made several scripts to automate send and receive files from Linux to Android and from Android to Linux:
https://github.com/wachin/adb-send-files

I don't believe adb shell supports tab completion.  It makes reference to a directory in a command, but if you don't know the path you will need to use adb shell ls command to list the directory before using the path in an adb push command.  For example, adb shell ls storage/9102-ABF4 will let you explore the external SD card that is on your device.
In terms of changing the working directory on your terminal, I don't believe you can do this because adb does not support interactive mode like nslookup.  You are using a shell (adb shell) within a shell (bash, PowerShell, cmd, etc).


text:
How to disable dm-verity on Android with "user" build type ROM?
I have One Plus 6T Android device which has a ROM of build type user. This device is rooted with Magisk and I want to disable dm-verity on this device. I have tried to run adb disable-verity but I got an error saying verity cannot be disabled/enabled - USER build
Is there any way to disable this?
Goal: Want to place customized sepolicy file under system_root directory. I have tried to do it with following commands:
C:\Users\GPU-Test>adb shell
OnePlus6T:/ $ su
OnePlus6T:/ # mount -o rw,remount /system_root
OnePlus6T:/ # cp /sdcard/selinux_policy_modified /system_root/sepolicy
cp: /system_root/sepolicy: Permission denied
1|OnePlus6T:/ # cp -f /sdcard/selinux_policy_modified /system_root/sepolicy
cp: /system_root/sepolicy: No such file or directory
1|OnePlus6T:/ # ^C
130|OnePlus6T:/ # exit
130|OnePlus6T:/ $ exit

C:\Users\GPU-Test>adb disable-verity
verity cannot be disabled/enabled - USER build

Also tried to disable Preserve force encryption and Preserve AVB 2.0/dm-verity checkbox but still the above commands have same result. Also on reboot these check-boxes enables again automatically.

can you please be more specific what your question is targeting, because usually you have already patched your device against dm-verity (Magisk Manager has a checkbox for)?

I have added more detail regarding why I want to do this and what I have tried.

why not use / instead of /system_root?

@alecxs on system-as-root devices Magisk mounts recovery ramdisk at /, not system partition. / is volatile filesystem.

@IrfanLatif thanks, "recovery" was the missing piece! Now this article makes sense to me "Magisk mounts system to ‘/system_root’ and bind mount ‘/system_root/system’ to ‘/system.’ " https://www.xda-developers.com/magisk-google-pixel-3-pixel-3a-android-q

@alecxs with Q things have again changed. Now system partition will be monuted at / but the files to be modified/added (e.g. init, init.rc, /sbin) will be overlaid using bind mounts. In each case target is to be system-less and detection-less.

I think I need to place sepolicy file directly into system.img and then flash it via fastboot system system.img command. I have tried lots of tutorial-like https://www.china-devices.com/forum/index.php?threads/how-to-properly-unpack-and-repack-android-system-img-for-sp-flash-tool.18739/ but I get an error like "Invalid sparse file format at header magi \n Failed to read sparse file
". I think these all tutorial are deprecated for new android images. Do you guys have any idea about any tool that can extract system.img?

@VatishSharma modifying system.img isn't a big deal but it makes no difference. Device won't boot with modified system.img if dm-verity is enabled. Let me write answer for you what you can try to disable dm-verity.

I'm going to give a general overview of how dm-verity and related things work on Android according to my limited knowledge. Situation might differ on different devices and ROMs.
HOW IS DM-VERITY ENFORCED?
dm-verity (Verified Boot and AVB) as well as dm-crypt (FDE) are targets of device-mapper feature of Linux kernel. dm-verity verifies the integrity of each block as they are read from block device; enforced by init_first_stage as per fs_mgr_flags set in fstab (1). On system-as-root devices (A/B and non-A/B), kernel is patched to force verity while mounting /system and /vendor if verify/avb flags are found in fstab device tree (dtb).
dm-crypt decrypts/encrypts data transparently when read/written from/to block device. FBE is based on a different kernel framework fscrypt; but both are managed by vold (which runs as a native service) if fs_mgr_flags contain voldmanaged.
WHERE FSTAB IS?
fstab has traditionally been a file on Linux to specify filesystems to be mounted on boot. It's a core component of fs_mgr functionality on Android.
On pre-Oreo releases fstab was in ramdisk. With Treble it was moved to /vendor (or /system/vendor) while the fstab entries for system and vendor (and odm) are moved to Device Tree Blob (dtb). Kernel exports dtb fstab entries in device tree directory at /proc/device-tree/firmware/android.
Some OEMs also put fstab in odm or nvdata partitions.
Source: Android Storage Device Configuration
WHERE DTB IS?
Device Tree is a data structure for describing hardware which is not discoverable to kernel. Device Tree Source (dts) can be converted to dtb (binary blob of DT) and vice versa using dtc. DTB is loaded by bootloader at boot time and passed to kernel so that it can discover hardware and create device nodes accordingly.
DTB is either:

Appended to kernel zImage or Image.gz in boot.img (2). It can be split from gzip archive using split-appended-dtb (sadtb).
Or in dtbo partition as some OEMs do. This can be checked with:
~# ls -l /dev/block/bootdevice/by-name/dtbo*
~# grep -C5 PARTNAME=dtbo /sys/dev/block/*/uevent | grep DEVNAME | sed 's/.*=//; s|^|/dev/block/&|'

Or at the end of boot.img after 2nd stage, or in odm partition (rare, some OEMs do).

Also if the device is non-A/B, dtb (from boot.img and/or dtbo partition) is also added to recovery.img in DTBO section after header, kernel, ramdisk and 2nd stage (3). However this doesn't matter for normal boot. But if the device is also system-as-root, Magisk needs to be installed in this recovery partition as the boot.img contains no ramdisk (4).
In case if DTB is not appended to kernel, dtb(s) are converted to dtb.img using mkdtimg. Same tool can dump back the image.
Source: Implementing DTO
HOW TO DISABLE DM-VERITY?
On userdebug ROMs, dm-verity can be disabled using adb. It modifies magic number of verity metadata block (5, 6) which is written after the last filesystem block on block device (system or vendor) (7). Quoted from here:

the absence of this magic number will halt the verification process

In case of AVB, adb modifies vbmeta header to disable hashtree image verification (8, 9). Quoted from here:

if the AVB_VBMETA_IMAGE_FLAGS_HASHTREE_DISABLED flag is set in the top-level vbmeta, then androidboot.veritymode is set to disabled

On user builds ro.debuggable is 0 and adbd isn't running as root. Also there are other differences like that of ALLOW_ADBD_DISABLE_VERITY, so adb won't disable dm-verity. Other approach is to remove verify or avb (10) flag from fstab. Quoted from here:

To verify the partition...
  ...
      In the fstab for the relevant entry, add verify to the fs_mgr flags.

Similarly to remove encryption, forceencrypt=, forcefdeorfbe= or fileencryption= need to be replaced with encryptable=. However encryption cannot be removed without factory reset (FBE too?), so unchecking Preserve force encryption in Magisk app will do nothing.
Some OEMs also use support_scfs fs_mgr flag and ro.config.dmverity=true property on devices with dm-verity enabled.
There are also some exploits discovered in bootloader and adb implementation of some OEMs which can be used to disable dm-verity on affected devices. However such security flaws usually get fixed over time with updates from OEMs.
OPTION 1
Set options in configuration file before installing Magisk:
~# echo 'KEEPVERITY=false' >/cache/.magisk
~# echo 'KEEPFORCEENCRYPT=true' >>/cache/.magisk

If installed, after unchecking Preserve AVB v2.0/dm-verity in app, Magisk needs to be reinstalled. Quoted from here:

in Magisk Manager, “Uninstall > Restore Images” to restore the images, check “Preserve AVB 2.0/dm-verity” box in Advanced Settings, then reinstall Magisk via the app.

OPTION 2
Use some dm-verity disabler zips like this.
OPTION 3
Figure out where the fstab entries of /system and /vendor are on your device.
If in ramdisk (pre-Treble):

Extract ramdisk, modify fstab and repack.
Or patch ramdisk directly:
~# magiskboot cpio ramdisk.cpio 'patch false true'

If in dtb:

If appended to kernel:

Extract boot.img
Split appended dtb(s)
Patch dtb(s).
Append dtb(s) to kernel
Repack boot.img

If in dtbo partition or in boot.img after 2nd stage, patch dtb.img and write back to partition or boot.img.

How to Unpack / Repack Boot or Recovery image and Ramdisk?
Use AIK or magiskboot.
How to Patch dtb?
Patch directly using magiskboot or manually convert dtb to dts, edit dts with any text editor to remove dm-verity flags, and convert dts back to dtb.
RELATED:

How Magisk works?
Android Device Partitions and Filesystems

In SAR devices launched with Android 10, I have built a kernel with avb flags(no verity flag found) removed from fsmgr_flags entries and made it permissive. Also empty the vbmeta with verification flag disabled. Is it enough for a dm-verity to be disabled? (I can't test it as twrp is not updated to Android 10 and Idk yet how to mount dynamic partition with rooted adb shell in recovery)

@VatishSharma Sorry I haven't tested with Android 10, so cannot say anything for sure.

Do you have idea of mounting dynamic partitions(I have made twrp and get rooted adb shell but yes its not updated for dynamic partitions and so lack mounting features)?

@VatishSharma no idea.

Do you have an idea how to disable dm-verity in an AOSP build? I assume it's a makefile value.

You can just edit the Magisk root package to ONLY disable the dm-verity flag. It's literally just commenting out a few lines of Magisk scripts, since the functionality is inherently present in Magisk. Here's the link to such a package: Download magisk-onlynoveritypatch.zip Boot into twrp, install from zip, and select this zip.

thx for sharing. unfortunately only registered users can download. and it's hard to register because there is no english captcha :(


text:
All system audio being transmitted over calls
So I have a Huawei Y9 (2018) running Android 9 with EMUI 9.1. Whenever I'm on a call (I've only observed this with Messenger calls so far), all the audio from my notifications and media (if any) also get transmitted over the call and the other person complains about having to hear them. I don't know what's going on really. Any help?

Check for the secondary microphone on the phone (usually, it is near the back camera or top of the phone). This microphone is used for noise cancellation. Do not block it with your hand while talking on the phone.

My apologies, I forgot to mention. This only happens when I'm using earphones.

Did you try with any other earphones?


text:
Live wallpaper selection on Pie?
I find the new Wallpaper app on Pie doesn't let you pick live wallpapers. Even when I downloaded the APK and installed it, it says 'cannot install'.
It's not as though 9 doesn't support them, the first time I installed a live wallpaper, I was able to click 'open' on the package installer and set it, but now since it doesn't provide an app icon I can't go back to it if I change to something else. I'm running the LineageOS 16 based Resurrection Remix custom ROM on a OnePlus 3.

Overkill - I had to install the Pixel 3 live wallpaper collection that weighs in at 159 MB. It lets me choose my own live wallpapers in addition to the built in ones (that made it so bloated).
I've marked this as the answer - but open to other alternatives too.

You should install a third-party launcher for your Android phone. This will enable you choose Live wallpapers. Your custom ROM launcher doesn't support live wallpapers.
Also, for future references, contact the developers of the custom ROM to include the ability to include live wallpaper option in their next versions.

Live wallpaper depends on the wallpaper selection app, not the launcher. If you paid attention to my post, I clearly said I am able to set a live wallpaper if I open the wallpaper app (not the wallpaper selector) right after I install it. Since it doesn't add a launcher icon, I can't open it again. The current wallpaper selector is directly taken from Google with no changes, and it only shows a few built-in wallpapers (presumably from Pixel) and my gallery pictures.

Please check here for "APK not installed" error: https://www.digitbin.com/app-not-installed-fix-error/

I paid attention to your post. Wallpaper apps don't add a launcher icon. Have you tried any other wallpaper pickers? I have had luck working with wallpaper apps like Wallzy which themselves integrate a wallpaper picker service with Live wallpaper option. Also, launchers have a wallpaper picking service within themselves and that's why I recommended doing an install.

I'd just like the default functionality back - I don't get why adding the stock live wallpaper picker for 9 doesn't work. Did you mean this - https://play.google.com/store/apps/details?id=com.phpmalik.wallzy ? Looks like a frontend for Unsplashed, which has its own app. Can it specifically let you set live wallpapers that you already have installed? I'm not interested in whatever downloads they offer.


text:
Android 9 "battery fully charged" icon flickers: What does it mean?
With my Samsung S10e phone fully charged, when I unplug it from USB then re-plug it in, the "battery fully charged" behaves like this:

appears and disappears a few time quickly
stays visible for 5 seconds
appears and disappears a few time quickly
stays visible for 5 5seconds
appears and disappears a few time quickly
stays visible forever

Question: What does that mean exactly? In particular, is it an indication that there is a kind of problem with the hardware or software?

https://www.androidauthority.com/maximize-battery-life-882395/ its a common software issue on many roms, no need to worry about

@alecxs: I read the entire article, it talks about how to maximize battery life. Would you mind explaining how it relates to the flickering/visible cycle I observed, and what ROMs do not cause that? If possible as an answer rather than a comment, so that people can vote on it. Thanks :-)

it is not related. Not sure if there is a list with ROMs, just my experience. it's a software loop, it disconnects charging when full, then it connects and start charging. Bad side effect: it also kicks adb shell every ~5 seconds. I have seen this many times


text:
Prevent unwanted automatic phone call
Before anyone tries to dismiss this question, I know of a identical thread, but that question is too specific about a certain behavior following a user interaction with the phone.
I am in search of a general explanation and solution!
The phone of my 11 yo child is a Huawei P8 Light, which made an automatic call, without any interaction beforehands. At 6 a.m. today my wife heard voices and thought she is crazy, but she could locate it. She picked it up, removed the loading cable and saw, that the child's phone called someone of the contact list!
My child cannot install anything without a technical permission (Google Family Link). Before I gave the phone to the child, it was wiped and reset by myself to factory settings. All updates are installed, including firmware updates.
What exactly does cause this behavior and how do I prevent it by some setting?
I do understand technical explanations (I am developer).

There is a far yet distinct possibility that this may be a screen touch issue. Does the phone open and close, etc. other apps too? If so, we may be dealing with a touch issue on the screen.
Another instance that I have experienced is: my friend had a phone that acted up random things when the phone was charging, meaning that when it was connected to a power source, be it a laptop or its original charger, the phone would do random things when on the table (without anyone touching it).
Also, as a third possibility, please perform a "clear cache" for the "phone" app in the "apps" list in your settings.


text:
OS-independent app loading problem
My phone has an odd problem, and I don't know where to start in diagnosing it. Several apps started having problems opening, taking a very long time (sometimes several minutes) to open; sometimes they won't open at all, and a reboot will be needed. Interestingly, once the app has been opened for the first time, it won't have problems again until the next reboot.
So I reinstalled the OS, and the new one is an entirely different version of Android. And yet, the problem was not solved! So I started thinking about a hardware problem (reading the disk? using memory?), but I wouldn't know how to diagnose what it is, and if it's solvable or not. Any hints are appreciated. I understand this will not be enough information to solve it, but I will answer questions.
The phone is a Samsung Galaxy Note 3 with Lineage OS (unofficial, but the problem is present on two different, independently developed versions of the OS).

is it related to user-installed app or does it even happen on a fresh clean rom with default settings?

Which Android/LineageOS version so you use? On some versions the app is converted to native code (OAT/ART) when first run. May be there is a problem with the cache of the converted apps?

Sorry for the late reply. @alecxs: it happens with many apps, including Gallery which comes with the OS. But I don't know what would happen if no apps were installed.

@robert: it initially happened with an old version of Android/Lineage; now I have Android 9 PIE and a recent release of Lineage.

can have various reasons, hardware issue, running out of RAM, maybe dalvik-cache is recreated each time, or maybe decrypting takes time, or just bad file system... best is try to analyze log files https://android.stackexchange.com/tags/logging/info


text:
Equivalent of the Control + F to search text in PDF
Is there in Android an equivalent of the control + F search in texts and OCR PDF? In browser we have "find in page" options. But for PDF I didn't find such option. Is there shortcuts to make such search as we can make with the dashboard in PC?

It depends on the app you are using to open PDF files.

Are you using Google's PDF viewer?  If so, there should be a magnifying glass on the top right where you can search from.

Fine. Thanks so much. I often use Adobe Acrobat.

Based on your comment that you often use Adobe Acrobat, the app offers the same process as Google's PDF viewer. When reading a document, you must click the magnifier.

You can then enter the word(s) you are looking for on the document.


text:
Bluetooth scanning is disabled
I bought an android car head. I can search and pair my phone with it, but form the unit itself cant search for the devices and it always empty list. Is there a way to enable scanning from the unit it seems it was disabled by the admin?

In settings , under connections wifi,turn off wifi there will be a option underneath about scanning  you can select Bluetooth and Wi-Fi scanning in the background on or off


text:
How to ping a local network host by hostname?
I recently wiped my phone and now I am unable to ping a machine by the hostname. Pinging by IP works.
I have a machine, let's say it is called NAS. From my Router and PC, ping NAS finds the machine. However, from my Android Phone, ping NAS returns ping: unknown host NAS.
I am rooted, so I went to /etc/hosts and added 192.168.1.### NAS and it was able to resolve NAS to an IP but what is the solution for making it ping all machines by hostname.
In my Wifi settings on the phone, DNS shows 3 entries: 8.8.8.8, 8.8.4.4, 192.168.1.1.

Related: How to reach local computer via machine name instead of IP?

SHORT ANSWER:
You would be able to ping a local host by name only if your Wi-Fi router (or some other local host) is running a DHCP/DNS server which does know the name of the host you are trying to ping. This is a screenshot from my router:

Also make sure your Android device is sending DNS queries to local server and not on internet. Android loves Google so much, so you will often find queries going to 8.8.8.8 (may be when router is advertising the IPv6 DNS server) as it's in your case. 192.168.1.1 must be the first (and preferably only) DNS. Configure static IP in Wi-Fi settings or if you have root you can use Android kernel's built-in firewall netfilter to force a nameserver. Since DNS uses UDP port 53, do a Destination Network Address Translation (DNAT):
~# iptables -t nat -I OUTPUT -p udp --dport 53 -j DNAT --to 192.168.1.1:53

Non-root solution which works for both Wi-Fi and Mobile data is to use a VPN app like Virtual Hosts which intercepts DNS traffic and makes queries to configured upstream DNS server.
On Android Pie+, you need to set Private DNS off because by default DNS over TLS (DoT) sends encrypted DNS queries on port 853 which can't be interpreted by ordinary DNS servers.
For more details see How to configure DNS properly?

DETAILS:
WHAT IS DNS
Network hosts (anything connected to network including computers, phones, printers, routers etc.) identify each other with addresses (IPv4 most common these days). Hostname - which maps to an IP address - is relatively easy to remember for humans. When a host wants to access other host by name, hostname needs to be resolved first to the corresponding IP address. This name resolution was easy in early days particularly before internet when the networks were smaller. /etc/hosts file on each host used to contain the IP vs. hostname mapping of all hosts on a network, still valid today. When network grew in size, having thousands and then millions of hosts, it was no more possible to maintain hosts file of an ever-growing network, so Domain Name System was introduced.
In simple words DNS consists of servers - one or more hosts on a local or public network - which maintain a huge hosts database. So one can configure the DNS resolver on his/her host to contact a specific DNS server (which in turn may contact other servers recursively) when it needs to resolve a name. IP address of DNS server (nameserver) is usually provided by DHCP server or can be set manually. There are a number of popular public DNS like 1.1.1.1 (CloudFlare) and 8.8.8.8 (Google) etc. One can configure DNS resolver to use desired DNS e.g. from GUI settings or using /etc/resolv.conf file on Linux but Android doesn't offer a very straightforward way to achieve this. See How does Android OS do DNS name resolution? for details.
LOCAL DNS SERVER
So now if you want to ping a local host by name, you either need to add an entry to /etc/hosts file on your phone or there should be some DNS server on your local network. Actually there would be already one. Most of the routers offer the services of DHCP/DNS servers in addition to acting as gateways. Even when you create a hotspot on your phone (an it works as a simple router), it runs dnsmasq (up to Pie) as its DHCP/DNS server. But in order to resolve local hosts the DNS server should be a resolver, not just forwarder.
DYNAMIC DNS WITH DHCP
Next thing is how a local DNS server would know the hostnames of all hosts on network. This belongs to collaboration between DHCP client and server. DHCP communication occurs using different option codes. Code 12 is the one which lets client send its hostname to server (or may also request for a hostname) when asking for an IP address. Windows and Linux hosts are usually configured out of the box to send their hostnames to DHCP server (1) . Since Android 8 DHCPDISCOVER and DHCPREQUEST packets don't include hostname, so Android hosts can't be accessed by hostnames this way. See How do I change the name of my Android device?
DHCP server then forwards the assigned IP along with received/assigned hostname to DNS server so that to update its database (2, 3). A quote from a router's advanced configuration:

Register DHCP leases in the DNS Resolver allows you to register DHCP static mappings. This, in turn, enables the resolving of host names that have been assigned IP addresses by the DHCP server.

Same is for dnsmasq:

Machines which are configured by DHCP have their names automatically included in the DNS

An alternate solution could be to configure your DHCP server to assign static IP addresses and set hostname for each IP. See this answer for a little more details on this.
DNS ALTERNATIVES
DNS queries are unicast i.e. a host requests a DNS server for name resolution by calling the later explicitly by its IP address. However it's also possible to call hosts by name on a local network without using hosts file or a DNS server. This is done using multicast DNS (a zero-configuration protocol) in which each host on network acts as client as well as server. When a host sends mDNS query to all hosts on network at multicast address 224.0.0.251 where <hostname>.local is, the host with name hostname itself responds with its IP address, so the communication starts (4).
Android does have mDNS built-in but it works only if an app makes use of NSD APIs. For instance adbd force starts mdns service (5) so as to easily access an Android device (e.g. Raspberry Pi) from PC. See this answer for details.
There are also other name resolution solutions like NIS and LDAP/AD usually used on large private networks or NetBIOS used by Windows's file sharing. But Android's Bionic libc doesn't provide a phenomenon like NSS to prioritize NIS, LDAP or mDNS over DNS. Android's resolver only looks for hosts file before going for DNS (6). So you have to go for one of the two.

Why this is not the accepted answer is simply beyond me

@Lorenzo because mostly people come here to get their problem solved, not to contribute to the community


text:
Android (Galaxy Tab 6) Will not reboot to bootloader
Im hoping someone can point me in the right direction. So I am in the process of attempting to unlock the bootloader on my Galaxy Tab 6. However, the device will not boot to the bootloader. I can use the Vol up + Home + Power to get to the menu options (Wipe cache, Wipe data, Reboot to bootloader etc..). However, the reboot to bootloader option simply restarts the device to the OS. I have no issue booting to the OS at all.
First I thought I had a corrupt bootloader. I used ODIN to reflash the stock OS, CSC, and BL to the tablet using the Samsung provided files.  in BL I selected BL_T580XXU3BRF1_CL13839138_QB18630808_REV00_user_low_ship.tar.md5 . In AP I selected AP_T580XXU3BRF1_CL13839138_QB18630808_REV00_user_low_ship_meta.tar.md5 , I left CP blank as there was nothing provided, and lastly for CSC I chose CSC_OXX_T580OXX3BRF3_CL13878383_QB18711126_REV00_user_low_ship.tar.md5 . As far as ODIN options go, I have used Phone EFS clear, bootloader update, NAND erase all, and re-partition. I have had no success though. The tablet boots and works fine other than not being able to boot to the bootloader. Its really strange. Can anyone provide any insight?

Samsung devices don't have a fastboot mode in the first place.

If thats the case, how would you unlock the bootloader?

I resolved it. I discovered that its a problem that was quite common with the T580. I was mistaken about fastboot being on there. The issue is actually with the version of TWRP that was being used. It it for the T580, but does not work. This file must be used -- twrp_3.2.3-1_sm-t580_29918.tar . That version works flawlessly.


text:
trouble maker when I write email or username
When I want to write email or username, or when I search for topics e.g. on stack overflow, when I begin to write, I see immediately on the screen things I wrote in the past and sometimes, despite that I write something else, the previous typings replace them. It appens when I write to buy on Amazon or when I want to buy an airline ticket, when I want to write tags on a stack overflow site.
How can I neutralize this "help"…?
I'm browsing with Firefox, with a Google keyboard, my phone is a mi Max 3 working with Android 8.1.

Perhaps is it linked with automatic remembering passwords or equivalent function of the browser

Please check the Firefox settings. There's a way to clear personal data, where you can chose which to clear and which to keep. You most likely want to clear form data (and maybe cookies as well, to get rid of some tracking beacons while on it). As I don't use Firefox on mobile, I cannot tell you where exactly that is.

I'll try thanks

And did you succeed?

No, sorry.  I need to find time to think about