Size limit exceeded - what does it mean?

Hi Guys, I got the below line as the only line in a log file of an Exchange VSS backup:

==>> Size limit exceeded, unable to transmit file. <<==

I'm just confused as ti whether it's a log file error (as in the log file is too big) or if this size limit is the cause of the failed backup - which failed because: "avtar FATAL <5155>: Backup aborted due to earlier errors. No backup created on the server."