When maintaining a TFS environment where WI’s become crucial in terms of development artifacts, you may notice an issue with removed AD accounts causing a problem where WI’s are not privy to updates because the account has been removed from Active Directory. This becomes a huge issue because updates to the WI are no longer supported.
Generally, this will throw the error:
TFS Error: TF20015, stating that a field contains a value that is not on the supported list
This leads to the requirement where a developer, even though they have gone onto greener pastures, has an invalid account value, within a value restricted field. Bad news bear.
Fortunately, there is a supported route you can take with TFS in order to overcome this issue. Using the ALLOWEXISTINGVALUE rule allows entered value to still be valid even if that value is no longer a valid value. By customizing the process template work item types and use this definition for the field with invalid values.
Bada bing, good to go!