When running the Report Services Sync, the rebuild of the database fails. The error that appears in the General tab is:
Failure during computation
Reason: The item already exits
This can be caused by obsolete data that exists in the database of Report Services.
1) Confirm that obsolete data exists is the database by downloading that attached diagnostic_tool.sql and running the query on the report server database using the Microsoft SQL Server Management Studio. If the query returns data, as seen in the image below, there is obsolete data in the database:
2) Run the following SQL statement in SQL Server Management Studio directly to remove the obsolete data
exec RawData.RemoveDomain <domain id>
3) Force rebuild the Report Services Database using the Report Services Control Panel.