Monday, April 29, 2013

Backlog board TF400898: An Internal Error Occurred.

After upgrading to TFS 2012 Update2 our customer start getting "TF400898: An Internal Error Occurred" when trying to view a product backlog board.

Event log at tfs application tier said:
Exception Message: The given key was not present in the dictionary. (type KeyNotFoundException)
Exception Stack Trace:    at System.Collections.Generic.Dictionary`2.get_Item(TKey key)
   at Microsoft.TeamFoundation.Server.WebAccess.Agile.Models.WorkItemSource.<>c__DisplayClassa.<GetCompleteWorkItemData>b__6(IDataRecord dataRecord)
   at Microsoft.TeamFoundation.Server.WebAccess.Agile.Utility.WorkItemServiceUtils.<GetWorkItems>d__c.MoveNext()...

...etc ..etc

As this is a known issue, solution is described here:

But... it didn't help. Yes, there was inconsistency and 2 possible work items states mapped to Complete board state, but after fixing CommonProcessConfig.xml and leaving only User Story work item in Requirements categories - error still kept coming.

It looks like if there are work items which have the "invalid" state, the board is not getting rebuilt. So, in this unlucky case the fastest fix is to create a new area, and make it the only and default area for backlog.Which practically makes the backlog (and the board) empty.

So, this time the board gets rebuilt successfully. Go to the board page and verify it. After that, just set default area(s) for the backlog the way it was before. Most likely you will need to correct columns for the board, but the annoying TF400898 will be gone.
Just click on Correct this now, and assign relevant states for the board columns.



  1. We had this exact problem and your fix worked. Awesome! Thanks for posting!

  2. For us it worked even simpler:
    1. Select 4 different other areas and set one of them default (without creating a new one)
    2. Go back to the Kanban board and refresh it -> Error should be resolved
    3. Undo the area selection and restore the original state

    Done :-D

  3. for me its not working :( Do we need to configure the features first?

  4. I find more easy solution on this site: (the post it's in English)

    Just replace newer DLL you may have with old one !!

    I'm not saying it will work 100% but replacing one single DLL and restarting IIS it's kids stuff. It may not work ? Yes, but you need to try ! This is life.

  5. The post is from 2013 and for TFS 2012U2.