Can't update Cyanogenmod on AT&T Galaxy S III

I updated to Cyanogenmod 10.1 RC 2 and can't update beyond it. When I try to update to RC5, I get:

assert failed: getprop("ro.bootloader") not matching
"I747UCDLK3" or "I747MVLDLK4" or "I747MUMBLK3" or "I747MUMBLL1"

Which naturally causes the update to be cancelled

Does anyone have a link that shows how to resolve this, or other suggestions to resolve it? Thanks.

Answer

The message is basically telling you that you don't have the correct bootloader version on your device; specifically, you most likely have an older ICS bootloader rather than the Jelly Bean one. You can read a bit about this on CyanogenMod's Google+ page, and the CM Wiki page for the S3 succinctly notes:

Going forward, CM10.1 is no longer compatible with ICS bootloaders on this device. Please update or else you will get assert failures in recovery.

You'll need to upgrade to a newer bootloader. This carries some amount of risk since it's one of the few instances where you could potentially brick a device, but the risk is still generally pretty small.

I found links to the newer AT&T bootloader on XDA that will work with CM 10.1. You can flash them using Odin or Heimdall by following these instructions:

1. 
   

   Go here http://forum.xda-developers.com/showpost.php?p=41503727&postcount=13716

   
   


2. 
   
   

   Put phone into download mode and then open Odin.

   
   


3. 
   

   Choose the PDA slot and then select the correct file for your device (AT&T is LK3)

   
   


4. 
   

   Hit start and wait until its finished.

   
   


5. 
   

   Done