If you receive an HTTP internal server error 500, when trying to invoke the GetStatus operation of the Rebuilder Web service (.e.g http://localhost/RebuilderService/RebuilderService.asmx?op=GetStatus or http://localhost:8080/Warehouse/v1.0/warehousecontroller.asmx?op=Reinitialize) then check that a previous attempt to rebuild the warehouse hasn't left the TFSWarehouse database in read only mode. If it is, then simply take it out of read only mode, and run the rebuild warehouse operation again.
Note you must then call the http://localhost:8080/Warehouse/v1.0/warehousecontroller.asmx Run method to update the warehouse.