I have a SQL 2012 server that is throwing the following error every 5 minutes or so:

Error: 17886, Severity: 20, State: 1.

The server will drop the connection, because the client driver has sent multiple requests while the session is in single-user mode. This error occurs when a client sends a request to reset the connection while there are batches still running in the session, or when the client sends a request while the session is resetting a connection. Please contact the client driver vendor.

I alert on all Sev 20 errors, so I can't just ignore this.

The good news is that I have some leads on how to fix it (seems like a connection string issue):

The bad news is that I have no idea which application is causing the errors!

The server has over 50 databases, from a wide variety of commercial vendors, contractors, or in-house developers. The error contains no details about which spid or login or hostname or database caused the problem.

I've tried looking at active spids (using sp_WhoIsActive) when the error is occurring, but there is too much activity on the server for anything to stand out (nor do I know what I'm looking for). Same thing with running SQL profiler - without knowing how to filter, I'm just seeing the firehose of data the server handles on an ongoing basis.

I am trying to narrow it down by figuring out which application teams have made recent changes, but that hasn't panned out so far.

Any ideas?

  • 1
    Does creating an extended event to log on queries with a certain severity show anything? This one for example Commented Mar 15, 2019 at 15:23
  • @RandiVertongen Well, it doesn't seem to capture any more detail than the errorlog (at least with the default script in that blog post). I'll play with the event properties, though, and see if anything there seems helpful.
    – BradC
    Commented Mar 15, 2019 at 15:47
  • Look for a non-zero request_id value in the sp_whoisactive result. That will narrow it down to the connections using MARS.
    – Dan Guzman
    Commented Mar 16, 2019 at 13:47
  • I know its an old question but did you find any answer? I have this error that seem to arrive from time to time and I didn't have it before. I have thousands of queries per second, I have absolutely no idea what is causing this error. Commented Jun 10, 2022 at 12:42
  • 1
    @DaniellePaquette-Harvey Sorry, these eventually went away on their own without any action from me; my best guess is that whatever application was causing them got updated? Wish I could provide more help.
    – BradC
    Commented Jun 10, 2022 at 15:03

1 Answer 1


Try to use

select * from sys.dm_os_ring_buffers

to get more details about source clients.


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