do you mean log.liveupdate?
it might be that definition on SEPM are corrupted. follow this link and let know if it helps?
http://www.symantec.com/docs/TECH166923
also try this
For Symantec Endpoint Protection 12.1, follow the steps below:
Open a command window, then browse to:
C:\Program Files\Symantec\Symantec Endpoint Protection Manager\bin
Type lucatalog -cleanup and press Enter.
Type lucatalog -forcedupdate and press Enter.
Run LiveUpdate to verify that there are no errors.