This SqlTransaction has completed; it is no longer usable.

Scenario: Using stsadm -o mergecontentdbs as a batch operation causes transaction logs to get filled up quickly.


Solution: 
Error in ULS - The transaction log for database 'Destination_ContentDBName' is full. To find out why space in the log cannot be reused, see the log_reuse_wait_desc column in sys.databases' 

Shrink transaction logs and retry operation.