Communication failure occurred during finalization of backup process


How to recover from a communication failure that occurred during the finalization of the backup process.


The backup ran for the normal length of time, transferred the amount of data expected and appears that it should have completed successfully however the backup indicates it failed with the error "Communication failure occurred during finalization of backup process".


This error may occur due to a variety of different reasons.  Understanding where in the backup job this occurs is critical for understanding how to determine the root cause of the error.

The Unitrends system uses two ports to connect to the Unitrends agent during a backup job.  First, port 1743 is used as a 'control' port.  The initial communication from the Unitrends system to the Unitrends agent occurs on the control port 1743.  The Unitrends agent negotiates a port to send data back to the Unitrends system, typically port 1745 is used as the 'data' port but this may be altered in the agent's master.ini configuration file (c:\pcbp\master.ini).

Now, once data is being transported over the data port (1745) the control port (1743) is relatively quiet outside of keep-alive requests until the backup nears completion.  Once all backup data is transferred, the agent creates a summary of the backup job, logs the summary in the backup's catalog (c:\pcbp\catalog.dir) on the protected server and the agent sends the summary to the Unitrends system over the control port (1743).  The error "communication failure occurred during finalization of backup process" indicates that either the backup summary was not received by the Unitrends system.



Typical causes and troubleshooting information:

1)  Backup was terminated or died before completing.  In this case, there would not be a summary at the bottom of the catalog.

  • Look for why wbps died in the event logs - look at the last modified time on the catalog and search the event logs for this date/time
  • Was the server rebooted?

2)  Winsock port was terminated or died prior to the backup completing.  Winsock ports can be terminated for a number of different reasons.
  • Review the event logs for the time between when the backup started and when it failed (start time and elapsed time can be seen in the backup record on the system).

3)  Was the server was under high load when the winsock port was terminated?  
  • Servers under high load can terminate less used winsock ports as a mean to recover server resources.

4)  Is there a DMZ, firewall or antivirus which may have determined the connection to be stale?  
  • There are typically configurations within a dmz, firewall and antivirus software that can be altered to avoid these disconnections.  

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