|Message:||The conversation with ID ‘%.*ls’ and initiator: %d references a missing conversation group ‘%.*ls’. Run DBCC CHECKDB to analyze and repair the database.|
The metadata layer returned NULL for the conversation group. The database has been corrupted in some way. One possible source of corruption is a disk error.
Run DBCC CHECKDB in repair mode to bring the database back into a consistent state. It may delete messages if necessary to restore consistency. Investigate system error logs to see if this error was caused by another failure in the system.