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InSource Solutions

TN MES118 Clearing the MESDB Database Sessn Table



This article from InSource shows how to clear a session id from Wonderware MES 2014 R3. An orphaned session may prevent the login from a client application.

  • Author: Rich Brooks
  • Published: 6/19/2017
  • Applies to: MES 2014 R3 and higher


The MESDB database includes a Sessn table which holds the currently active client information.  A record is added to the Sessn table when the application is opened.  The Wonderware MES Service is responsible to clear out any records after 10 minutes of inactivity.


Shutting down the MES Service improperly may prevent the session records from being cleared.  


This may prevent a client from logging in from one of the applications as listed below.


Delete the problem record from the Sessn table by filtering on the session_id.


Restart the MES Service after the record is cleared.  You should now be able to log into the application as expected.