Symptoms

The following error message is seen when trying to manually start a K2 workflow on an item on a list or library containing 110 columns:

"An unexpected error has occurred while trying to resolve a value for Resolver ID DGUID]"
 

Diagnoses

This seems to only happen on lists/libraries with 110 columns. Other lists/libraries with less columns seem to work when starting a K2 workflow manually against an item. This seems to be a problem with the REST call that K2 is making from our K2 for SharePoint broker back into SharePoint to grab information about the item the workflow is being started on, and the length of that request. SharePoint will cut off the REST query before the end of the call, which prevents certain parameters from being sent in.
 

Resolution

This issue is consistently reproducible both in SharePoint 2013 on-premises and SharePoint Online (O365). However, the issue can only be remedied in an on-premises environment.

To resolve the issue, the following changes to the below parameters can be made in the SharePoint Web Application web.config file where such lists/libraries exist with 110 columns:

<requestLimits maxUrl="40960" maxAllowedContentLength="2147483647" maxQueryString="4294967295"/>
<httpRuntime maxRequestLength="51200" maxUrlLength="40960" maxQueryStringLength="2097151" requestValidationMode="2.0" />

This allows for long URLs to be received without a cutoff into the SharePoint Web Application so that K2 can retrieve the information needed about the item to start the process.