[Moto X General] mastarifla:
It seems like there needed to be a thread dedicated to the issues that users have been seeing with this recent OTA, as it seems like there has been a few problems with updating if you ever used Motorola's Stock 5.1 Image, I'll begin by listing the steps necessary to successfully apply the OTA update regardless of what software version you are currently running, there is also a TWRP System Image for those of you who don't want to go through the fastboot process or return to stock

Official OTA Update Procedure

1) Use TWRP and make a full backup, then connect your phone to your computer and transfer the backup files to your computer

2) Reboot your phone into the bootloader, either by doing adb reboot-bootloader or the physical key combination (power off then press and hold the power and volume down key for ~4 seconds)

3) Download the Stock 5.1.0-LPA23.12-15.0 Image from here, do NOT use Motorola's Recovery Image to do this procedure, it will fail, as the hashes are not what the OTA is expecting for the system.img, and extract the contents to a folder on your computer

4) Download the OS relevant attached mfastboot zip and unzip the contents to the same folder on your computer (if you are having issues with mfastboot try reefuge's version and see if it helps!)

5) Open up a command prompt in the directory and use the following commands to flash the 5.1 Stock Image, erasing the userdata partition is not required but it is highly recommended, as you can easily restore the TWRP data partition after doing these steps if you want your personal data back

[B]not required, but recommended![/B]
mfastboot erase userdata
[B]required[/B]
mfastboot erase cache
mfastboot erase customize
mfastboot erase clogo
mfastboot flash partition gpt.bin
mfastboot flash motoboot motoboot.img
mfastboot reboot-bootloader
mfastboot flash logo logo.bin
mfastboot flash boot boot.img
mfastboot flash recovery recovery.img
mfastboot -P flash system system.img
mfastboot flash modem NON-HLOS.bin
mfastboot erase modemst1
mfastboot erase modemst2
mfastboot flash fsg fsg.mbn
mfastboot reboot

6) Reboot your phone and do your initial 5.1 phone setup, and then immediately check for System Updates

7) Download the OTA and select to install the OTA

8) Rejoice in your completed OTA update, if the update fails to install, upload the recovery logs (or tell us the problem) and we will try to help!

9) You can now install TWRP and root if desired, and restore your TWRP data backup if you erased it beforehand

TWRP System Image

The TWRP System Image can be used instead of trying to apply the OTA update, this is a backup of my own phone's system partition after doing the OTA update, so it's already on 222.27.5...

Alright, after quite a bit of time uploading...

Here is the TWRP System Image

1) Download the Stagefright System 222.27.5 TWRP backup from the above link

2) Unzip the Stagefright System 222.27.5 folder to your computer

3) Copy the Stagefright System 222.27.5 folder to your phones internal storage, to the TWRP/BACKUPS/TA0000008VJ/ directory

4) Reboot your phone into recovery (TWRP)

5) Click Restore and select the Stagefright System 222.27.5 folder

6) Verify that the System partition is selected and then Swipe to Restore

7) Clear your cache

8) Boot into system and enjoy the new patch :)

_