Symptoms
Web Part Error: A Web Part or Web Form Control on this Page cannot be displayed or imported. The type SourceCode.Workflow.TaskList.WebPart.TaskListWebPartFactory, SourceCode.Workflow.TaskList, Version=4.0.0.0, Culture=neutral, PublicKeyToken==MYKEY] could not be found or it is not registered as safe. Correlation ID: GUID].
I followed the directions to resolve this issue per this article: http://community.k2.com/t5/K2-blackpearl/K2-for-SharePoint-2010-Worklist-WebPart-Error/ta-p/78949
Diagnoses
This error could be due to 2 reasons:-
1) Missing assembly
This assembly "SourceCode.Workflow.TaskList" does not exist in your Global Assembly Cache (GAC) on SharePoint Wfes.
2) Assembly not registered as part of Safe Control.
Check the web.config of this SharePoint site. Look for SafeControls section, here is an example of SafeControl section:-
......
Resolution
The TaskList DLL file was not deployed during the blackpearl upgrade. Customer ran the K2 Blackpearl SetupManager and selected ’Repair’ from the installer file on all WFEs including the Central Administration machine, and reran the K2 for SharePoint Configuration Wizard on the Central Administration machine. This resolved the issue.
