When OTA update our version of Android, if at the end of the process we get an error and no way to update, would be very interesting open the update log to know what happened and see why you can not update.
To open the log of failed events OTA updates, We need to be root and use any file browser applications such as root browser.
Once you have installed, we enter the cache folder recovery last_log. Error files are generated in here and always will be the last attempt last_log, previous attempts will always be last_log.1…last_log.2…etc…
If we click on the latest, then select Open as – text file and then in RB Text Editor or another text editor that allows open…below you have the example of my last OTA failed in nexus 4
Thanks to this, I can identify the problem, and it is clear that I can not update android for the last error at the end of the text marked in bold. The ruling is to check the file build.prop, that does not match the one expected to be the original, come on, build.prop that has been modified by another application and does not match what was expected, giving the error.
If we now go to system / build.prop and open it with a text editor, in my case I see end of text, some lines that should not be added, caused by the application Pimp my rom (if I had done the backup before modifying things with the app, You could restore that file and I eliminate this modification…)
There is an application that can be useful figuring out OTAs failures Failed, is called OTA Verifier. We installed and we click on select file, and seek the .zip file is in the directory cache. Hold down the zip finger and leave a menu that puts “verify ota.zip”…then do the analysis and tell us where the installation fails. It is quite complete.
Last_log end of file:
Finding update package…
I:Update location: /cache/6136cbe0fb21994b8bd463d137ac75b953ba8e9b.signed-occam-JWR66Y-from-JWR66V.6136cbe0.zip
Opening update package…
I:read key e=65537
I:read key e=65537
I:2 key(s) loaded from /res/keys
Verifying update package…
I:comment is 1606 bytes; signature 1588 bytes from end
I:whole-file signature verified against key 0
I:verify_file returned 0
Verifying current system…
file “/system/build.prop” doesn’t have any of expected sha1 sums; checking cache
failed to stat “/cache/saved.file”: No such file or directory
failed to load cache file
script aborted: assert failed: apply_patch_check(“/system/build.prop”, “e336e937ec01a4e2fcb60d3659e296a30701ebf9”, “b14efd4ddb55a476ba46fb51df7a230d829cab1d”)
assert failed: apply_patch_check(“/system/build.prop”, “e336e937ec01a4e2fcb60d3659e296a30701ebf9”, “b14efd4ddb55a476ba46fb51df7a230d829cab1d”)
E:Error in /cache/6136cbe0fb21994b8bd463d137ac75b953ba8e9b.signed-occam-JWR66Y-from-JWR66V.6136cbe0.zip
I:Saving locale “is is”