For years I have researched and tried to resolve the continuing occurrence of JRUN errors on my ColdFusion MX 6.1 Web application servers.  I found several band aid solutions, and many suggestions that were just not the cause of the problem.  Alas!  I have figured out why this happens and how to prevent it.

If you are experiencing JRUN Error Connection Closed, there is one simple thing that you need to do: For every Microsoft Access data source that you setup, under "Advanced Settings", you need to check the box that is labeled "Limit Connections", and you need to restrict connections to 1.  This is because the ODBC driver for Microsoft Access was not designed to handle multiple connections in a live environment since Microsoft Access was never really designed for higher level applications.  The driver simply crashes when a second connection is opened.  So, your settings should look like this:

 

In case this doesn't fix your problem, here are some links to other possible causes of JRUN Errors.

• http://kb.adobe.com/selfservice/viewContent.do?externalId=tn_19301