Nexus 4: Lost superuser rights after an update to 4.2.1 - how can I get them back? A couple of weeks ago, my rooted Nexus 4 was updated from 4.2 to 4.2.1. Now it still seems to be unlocked (open lock symbol while booting), but I've lost my Superuser privileges.


Is there any way I can get the SU privileges back without wiping my phone?
If not, what's the best way to backup all or most of the data before going through the SU process again?
Finally, how can I prevent this from happening again with the next update?


Thanks for your help!
Just re-root. Your bootloader is still unlocked, so nothing is preventing you from doing so. The Nexus Root Toolkit should do the heavy lifting for you if you want (just press "Root"). Manual steps would be:


Download a custom recovery, like ClockworkMod, and save it to your computer
Download the Superuser/su package for ARM and copy it to your phone
Reboot into your bootloader, either by holding Volume Down while turning on your device or by issuing adb reboot bootloader from a PC (plugged in via USB with debugging enabled on the phone)
Use the fastboot utility to install the recovery image from your PC via:

fastboot flash recovery /path/to/recovery.img

Reboot into recovery (boot into your bootloader, then press either of the volume buttons to cycle to "Recovery" and press power).
Install the the Superuser zip file from your recovery menu
Reboot. You now have root.


In general, if you don't want to lose root, don't install OTA updates. You can try apps like OTA Rootkeeper or Superuser's in-built functionality, but there's no guarantee that it will work since it depends on exactly how the OTA is applied. Some devices (the Kindle Fire is one example) will actually wipe the entire /system partition when performing an update, making OTA Rootkeeper apps useless. The only guaranteed method of updating and keeping root would be to wait for a repackaged (rooted) version of the OTA to appear on somewhere like XDA and then flash that from your recovery, or repackage it yourself.