This article was created in response to a support issue logged with K2. The content may include typographical errors and may be revised at any time without notice This article is not considered official documentation for K2 software and is provided “as is” with no warranties.


After applying MS Updates, the K2 service may crash, and/or fail to start. This may occur when attempting to deploy a workflow, or when restarting the service.


In the server logs, you will see the following message:

Application: K2HostServer.exe
Framework Version: v4.0.30319
Description: The process was terminated due to an internal error in the .NET Runtime at IP [SOMETHING] with exit code 80131506.

An end user deploying a workflow will see the message: "An existing connection was forcibly closed by the remote host."

This happens in multiple MS Updates, affecting .NET 4.6 and .NET 4.7. Some MS Updates believed to cause this issue:



K2 blackpearl 4.6.11: There is a codefix available for 4.6.11. Please contact K2 Support to request this codefix.

K2 blackpearl 4.7: The issue has been fixed in the K2 4.7 November 2017 Cumulative Update Fix Pack 5 and later.  See KB002132 for details. The fix has also been included in the K2 4.7 March 2018 Cumulative Update. See KB002261 for details. 

K2 Five: The issue has been fixed in the K2 Five RTM Fix Pack 3 and later.  See KB002137 for details. The fix is already included in K2 5.1.

Download the latest 4.7 Cumulative Update, or contact K2 Support to get the relevant fix pack for K2 Five.

Alternatively, you can uninstall the MS patch(es) involved.

The .NET Framework 4.7.1 version was released in October 2017 by Microsoft. More details can be found here