Symptoms

While accessing K2 Worklist webpart or the K2 app settings, you receive the following error message:

The file '/Designer/Runtime/_trust/spauthorize.aspx' does not exist.

The same error message appears while accessing the K2 list settings (SP list > K2 icon on ribbon).
 

Diagnoses

Redirecting to the wrong URL
Cannot find a default Runtime/runtime URL
This is a known issue as documented in K2 for SharePoint 1.0 (4.13350.1.0) Known Issues List

 

Resolution

Follow the steps from KB mentioned above you can resolve this issue after completing the registration wizard and changing the Designtime to Runtime.