Symptoms

We have an existing K2 workflow that has been working in production for several months. Users are now getting an error when opening a task assigned to them with a message such as: “Worklist item could not be opened. This site is not allowed to open the worklist item with serial number”.

The task is assigned to individuals who are in the Domain Users AD group, and that group has been given process rights of Start/View/View Participate.

We have verified that the users have been assigned the K2 task, and using the SO Testing Tool UMUser GetGroupUsers SO shows they are in the Domain Users group.

Diagnoses

In a meeting with the customer, we noticed that the worklist item URL contained the incorrect Server name. We found that the string table for the process had been changed, altering the Smartforms Runtime URL to use the wrong server.
 

Resolution 

We edited the Smartforms runtime URL value to correct the server name, so future process instances would not be broken in the same way. The users were able to edit the worklist item URL manually when trying to open the item, which allowed them to action the item.