TFS Work Item Customisation, and the TF26201 error

With the work I’ve been doing defining custom Work Item Types in TFS lately, I came across an interesting problem, to do with TFS’ TF26201 error, so I thought I’d mention it here, along with how I went about sorting it out.

So, having finished the first cut of the first work item type definition, I went to test it, and discovered that some when changing a test work item to certain states and attempting to save, Team Explorer would fail to save in the new state, with an error:

“TF26201: This work item has unsupported fields, or user does not have permissions”.

I googled the error (as you do) and didn’t have much joy. A couple of people found this problem when doing stuff with the W.I.T object model, but I couldn’t find anything about tracking down whats wrong when testing custom work items using Team Explorer. So, to figure out what was causing the problem, heres what I did:

 

1. Edit the work item type definition file, commenting out all field rules in the “To” state, and upload back to server
2. Try saving item to the new state, which should work now, as there are now no field restrictions in place for that state
3. Uncomment all the field rules from the “To” state again, and again upload to server
4. Open work item and try to save as-is, without changes
5. Team Explorer will complain about specific fields, instead of the general error message
    

For the record, the reason I was receiving this error was because I had some fields in a couple of states with “<EMPTY />” rules, scoped to the STATE. Removing these fixed the issue, and I’m going to try scoping these to the a specific TRANSITION instead.