VSS_E_WRITERERROR_RETRYABLE

Can you also check the application event log to see if you can find a more detailed error in there ?

You should check the Event Log to see if there are any errors listed there.  The "retryable error" is not an easy one to diagnose.

Also suggest to enable verbose Exchange VSS Writer Event logging via PowerShell.
To do this from a PowerShell commend:

C:\Windows\system32>get-eventloglevel *vss* | Set-EventLogLevel -Level expert
C:\Windows\system32>get-eventloglevel *vss*

Identity /   EventLevel
-----------------------------
MSExchange Repl\Exchange VSS Writer     /   Expert

To set this back to normal when it has captured the log, again from a PowerShell command:

get-eventloglevel *vss* | Set-EventLogLevel -Level lowest

• VSS_E_WRITERERROR_RETRYABLE: indicates that retrying without reconfiguration might work. If the writer continues to return the error after several retries, try restarting the service that hosts the writer. The following writers are hosted in the VSS service: registry writer, COM+ class registration database writer, shadow copy optimization writer, and Automated System Recovery (ASR) writer. If the writer belongs to an application that hosts the writer in its own process, try restarting the application. Windows Server 2003 and Windows XP: The following writers are hosted in the VSS service: registry writer, COM+ class registration database writer, application event log writer, and Microsoft SQL Server 2000 Desktop Engine (MSDE) writer

• Also this indicates a previous error had occured and now it is stable, you can again run the backup and check.

"Exchange Replication Service is stable"

Hi lyso1985 

Could you please attach the nmm.raw file from the node failing as well as the one from the main node where the DAG resource is currently running?

Does config checker pass with no issues?

Thank you,

Carlos