Symptoms

We have recently installed K2 on SharePoint 2013, smartforms and smartform webpart seems to be working fine but K2 worklist webpart is not working.
It throws the following error, "Value cant be null. Parameter Name: token".


 

Diagnoses

SharePoint 2013 running in SharePoint 2010 compatibility mode.
 

Resolution

Sent DOc: "SharePoint and Classic web parts using the K2 API with claims.doc".
Converted the WebDesigner virtual directory to a Web Application.