Query execution failed for data set 'IterationParam'. (rsErrorExecutingCommand)

Got this when restoring TFS to test the disaster recovery. The solution is as follows from MSDN forums:

This might be due to a known Analysis Services issue that can be fixed by applying the SQL Server 2005 KB914595 HotFix from http://msdn.microsoft.com/vstudio/teamsystem/downloads/

If this does not work, I would recommend deleting the cube and recreating the warehouse by following the following steps:

Step 1:
Stop the SQL Server Analysis Services – Use Management Studio - Connect to Analysis Services - Right click on the Analysis Server and select Stop.
Make a copy of the Analysis Server “data” folder for backup. Program Files\Microsoft SQL Server\MSSQL.2\OLAP\Data
Delete the Data Folder
Restart Analysis Services.

Step 2
Run the setupWarehouse command from the application tier:
C:\Program Files\Microsoft Visual Studio 2005 Team Foundation Server\Tools\Setupwarehouse.exe -o -mturl http://|APP_TIER|:8080 -c warehouseschema.xml -s |DATA_TIER| -d TfsWarehouse -a |DOMAIN|\|SERVICE_ACCOUNT| -ra |DOMAIN|\|REPORTING_ACCOUNT|

|APP_TIER| is the name of the app tier server.
|DATA_TIER| is the name of the data tier server
|DOMAIN|\|SERVICE_ACCOUNT| is the account used for TFS Services (set in your domain)
|DOMAIN|\|REPORTING_ACCOUNT| is the account used for TFS Reporting (set in your domain)

Wait for this process to complete.

Step 3:
From the application tier server
Open http://localhost:8080/Warehouse/v1.0/warehousecontroller.asmx.
Click Run and then click Invoke.
Open http://localhost:8080/Warehouse/v1.0/warehousecontroller.asmx.
Click GetWarehouseStatus, and then click Invoke.
Wait for the service to idle. The service should return Running Adapters, ProcessingOlap, and then idle. The four possible return states are:
Idle: The warehouse is not processing.
RunningAdapters: The adapters are applying schema changes or pulling data into the warehouse.
ProcessingOlap: The warehouse is processing schema changes or data changes in the OLAP cube.
Blocked: The warehouse is blocked.

Step 4:
Process the TFSwarehouse in Analysis Service using Management Studio.


Credit to Othmane Rahmouni-MSFT
Forum Post : Warehouse Cube Won't Process - B3Refresh Upgraded OK

**Further findings**

If the above does not solve your problem, then it could be due to simple permissions on the datasources.

To verify this, open any report in the TFS portal. If you are not presented with the normal params i.e. it asks for a login and password, or if it complains about not being to connect to the TFSOlapReportDS then this may be due to security.

By default, SSRS installs using "Credentials Supplied by the User Running the Report". This does not seem (in my case) to work with TFS. To correct this issue you must :

1. Go to site settings.
2. Select the TFSOlapReportsDS Datasource
3. Create (or check) the ConnectionString. It should be along the lines of : Data source=TFS_SERVER;initial catalog=TFSWarehouse
4. Change the Connect Using to use Credentials stored securely in the report server. Set this to use your fixed TFSReports login and password.
5. Check Use as Windows credentials when connecting to the data source
6. Repeat this for TfsReportDS

All should work now !