This is the strange error message that I encountered from a mirroring principal server on which an alert is set to report to DBA team if error number “32040” is detected. The official Microsoft description of this error message can be found here at Microsoft’s website. And usually this error is reported only when unsent transactions are piling up at the principal box. However, the mirroring monitor showed perfect 0KB of “unsent log” and 00:00:00 of “oldest unsent transactions”.
To resolve this issue, I used the “pause and restart mirroring” approach that somebody mentioned here at SQLServerCentral’s forum. The exact scripts are as follows:
ALTER DATABASE [DBNAME] SET PARTNER SUSPEND GO ALTER DATABASE [DBNAME] SET PARTNER RESUME GO