TF200031: An error has occurred when trying to add or synchronize the following user identity: {0}. The identity contains ...

TF200031:  An error has occurred when trying to add or synchronize the following user identity: {0}. The identity contains one or more XML characters that are not valid in the account name, the distinguished name, or the the mail address.  The identity cannot be added to Team Foundation Server. For more information about naming conventions, see the topic "Naming Restrictions for Team Foundation Server" on the Microsoft Web site (http://go.microsoft.com/fwlink/?LinkId=77936).