Note: This Article is important for VSTS administrators when the report service account that is used by VSTS is being changed.
When you change the reporting services service account (referred to by the placeholder account name TFSReports) for Team Foundation Server, you must also update credentials for the Reporting Service data sources after you run TfsAdminUtil ChangeAccount on the TFSService account.
To update credentials for the Reporting Service data sources:
1- Start Internet Explorer. Open http://[ApplicationTierServerName]/Reports. as it is shown in Figure1, in my case the AT server name is : http://tfsrtm/Reports
2 - On the Contents tab, select TfsReportDS
Figure1: the SQL Server Reporting Services Home
3- On the Properties tab, update the User name and Password for Credentials stored securely in the report server, and then click Apply. This is depiocted in Figure 2
Figure 2: Changing the Credential Stored in Report Server
Repeat the steps three (3) for TfsOlapReportDS. Its link is shown in Figure1 too.