A previously working replication job begins failing with the above error message.
Open a putty session, with root authority, to both the Source and Target ESX hosts.
Locate the directory where the vm resides on both the Source and Target ESX host.
List all the files in the directories using ls -alh
Remove any files ending in .vzmap .vztemp (for example rm -r *.vzmap)
Remove any files containing vzundo
Remove .vzcids if it exists
The replication job should run now. It may take longer than normal as vReplicator must rebuild the .vzmap files.