[Microsoft][ODBC SQL Server Driver]Communication Link Failure


  • Several of our customers are getting a message intermitantly throughout the day where the connection is closed.  The message being generated is [Microsoft][ODBC SQL Server Driver]Communication Link Failure.


    These messages started in the last two weeks.


    Thanks for any direction that can be thrown my way.



    Tuesday, November 27, 2007 10:26 PM

All replies

  • Hello David.  We've started to have a similar problem.  Our processing center is currently not very busy, as our major load starts after the beginning of the tax season.  For this first time since we switch to SQL Server, we've started seeing unexplainable network connection drops between our client applications and our SQL Server.  Currently, our SQL Server is 2005, SP2 with cumulative updates package 3 for SQL Server 2005 SP2 (a cumulative SP2 upgrade package).


    We never saw this problem on SQL Server 2005, SP1, which is what we used last year, nor on previous versions of SQL Server.  We've seen the problem on both 32-bit and 64-bit SQL Server machines.  And, the problem appears to ocurr only with connections that have been idle for a while.  Note that we have not changed the default settings for SQL Server 2005 TCP/IP connections.  The KeepAlive option is set to 30000 ms.


    What we WANT is for the behavior of our SQL Servers to go back to being what is was prior to SP2 or SP2 with the cumulative update package 3 (we are not sure which is the problem).  That behavior was that inactive database connections were not timed out/dropped.  The connection was not closed until the client closed it (either gracefully or ungracefully).  We just have too much old code that depends upon this behavior.


    PS.  to MS people -- Any help with this issue will be greatly appreciated.



    Thursday, December 13, 2007 9:22 PM
  • After Googlizing and searching the whole internet, I could not come to any exact conclusion.


    I happened to see the application log in the Event Viewer...and lo and behold!

    I saw Automatic Updates were sometimes starting and stopping the SQL Server(Instance) Services. When Automatic Updates were disabled the errors reduced drastically.


    Another reason was that the network card was constantly connecting and disconnecting. We replace the network cards and the error is as good as gone.


    So I have written this so as to provide my solution to anyone who had this menace of a problem

    [Microsoft][ODBC SQL Server Driver] Communication Link Failure


    This is how I solved this problem.


    Best of Luck!!!






    • Proposed as answer by CrowderSoup Friday, March 02, 2012 6:33 PM
    Tuesday, November 25, 2008 6:13 AM
  • Thanks! I'm having the same issue. I'm going to look into the Auto Updates and such. I wouldn't have known where to look if you hadn't said anything!
    Friday, March 02, 2012 6:33 PM
  • Hi,

    I am also getting the same error in SQL Server 2008 R2.

    Could you please explain on the "auto update" part so that I can also follow the same steps and resolve the issue ?



    Saturday, September 10, 2016 5:12 PM
  • I am also getting the same error in SQL Server 2008 R2.

    Could you please explain on the "auto update" part so that I can also follow the same steps and resolve the issue ?

    Don't piggyback to a thread from 2007, but start a new thread, clearly describing your problem.

    The error Communication Link Failure is due to that connection to SQL Server was lost and there are of tons of reason why this could happen. Check in the SQL Server error log if there are any stack dumps that coincides with these errors - that's one of the possible reasons. Other reasons include flaky networks, That is, reasons with no relation to SQL Server at all.

    The autoupdates discussed in the thread are the updates from Windows Update. Obviously, you don't want it to set to automatically apply updates and reboot a server. The updates should be applied in maintenance windows.

    Saturday, September 10, 2016 7:07 PM