We recently experienced the below error message on a Exchange Database in a DAG scenario where the database had 2 servers that had copies of the database. The server that the database in question was mounted on had a blue screen and the database attempted to fail over to the secondary copy but was unable to mount with the below error.
“Incremental seeding of database DatabaseServername encountered an error. A full reseed is required. Error: The Microsoft Exchange Replication service failed to determine if the log files in database ‘Database’ are divergent from the source copy on server ‘Servername‘. Error: An error occurred while processing a request on server ‘ Servername ‘. Error: Database ‘Database GUID’ was not active on source server ‘ Servername ‘.”
We couldn’t get the database mounted on our server that had the secondary copy of the database even if we ran the mount-database command where we except data loss.
As this was an urgent situation we managed to get the database mounted again by removing the database copy of the server that blue screened, this allowed us to mount the database