I ran into an issue the other day where the Microsoft Exchange Mailbox Replication Service would not start on one of the servers in a DAG.  The service would timeout when trying to start as seen in the System event logs.  No other real good information to go on.  Issue persisted after a reboot as well, so it wasn’t something that was a one-off cleared out by a reboot.  AV was disabled as well as some other ideas to no avail.  

I started looking at the files thinking maybe there was some corruption and sure enough that was the issue.  The file highlighted in yellow was originally named MsExchangeMailboxReplication.exe.config and was only 1Kb in size.  Comparing to another server in the DAG, the file should have been 22Kb.  Not sure what happened exactly to cause this, but after renaming the file with the appropriate .wtf extension and copying an intact MsExchangeMailboxReplication.exe.config file from one of the good servers in the DAG, the Microsoft Exchange Mailbox Replication Service was able to start and all was good again.

Until next time…