After upgrading Team Foundation Server 2012 to Update 2, we started to get an error when opening a PBI or Bug via the web portal. This was the error:
TF400898: An Internal Error Occurred.
Not terribly helpful… Anyhow, after searching the web there were some similar-sounding issues but none of them helped. In this case it turns out the problem was that non-Administrators received the error, but Collection Administrations did not get the error. I’m not sure why that is the case yet, but will continue to look into it.
As a temporary solution for anyone with this issue, try giving increased permission to your team.