The following is a snapshot of the error that you might see if the Reporting Services data sources are not updated when the account is changed or updated:

Reporting Services Error

  • An error has occurred during report processing. (rsProcessingAborted) Get Online Help
    • Cannot impersonate user for data source 'TfsOlapReportDS'. (rsErrorImpersonatingUser) Get Online Help
      • Logon failed. (rsLogonFailed) Get Online Help
        • For more information about this error navigate to the report server on the local server machine, or enable remote errors

SQL Server Reporting Services

 

Most of us are probably already aware of this, but this question comes up quite often. If your Reporting Services service account has changed because you moved your Team Foundation Server installation or if you are using a different account, you will need to run TfsAdminUtil ChangeAccount.

In addition to this, you will also need to update the password and/or username for the TfsReportDS and the TfsOlapReportDS data sources manually using the Reporting Services web site at: http://<ATMachineName>/Reports/

More documentation on this topic: http://msdn2.microsoft.com/en-us/library/ms252480(VS.80).aspx