BBT/VSS Warning Message: Block Based Driver communication failure

This article discusses information regarding following warning message during an Incremental Job with transfer option BBT/VSS selected:

Warning: Block Based Driver communication failure (SwitchToServerSync)

If the process of incremental checks on the state of the volume results in either the last incremental being run a long time ago or the volume check does not return expected values, then it rebuilds the volume by comparing the volume synchronization state using  what is known as server sync. The transfer method is the same (BBT/VSSBBT) as the one selected when the job was configured. It’s just that since the return code from the volume check was not as expected it goes ahead to rebuild the volume.

This is functioning as designed and the warning message can be ignored.