Microsoft.ReportingServices.Diagnostics.Utilities.ReportServerStorageException: An error occurred within the report server database. This may be due to a connection failure, timeout or low disk condition within the database.
I ran into this a couple of days ago while attempting to configure a SQL Server 2012 Reporting Services instance. As it turns out the Ops team had configured this reporting server with a named instance of sql server to house the reporting services databases which installed as ReportServer$InsntanceName and ReportServer$InsntanceNameTempDB. I went through a rather lengthy migration process from SQL Server 2008 R2 reporting services to the new SQL Server 2012 instance. Everything looked to have migrated fine with a few tweeks to security. Everything except the report schedules. When attempting go launch the report schedule I received a rather perplexing message stating that there was database error and that it may be due to a connection failure, timeout or low disk space condition. I found this odd since all other functionality of the report manager was working fine. I checked the database error logs and system event logs and saw nothing. Finally I turned verbose logging on for SSRS and recreated the error. Upon examining the detailed SSRS log I found the culprit “Invalid object name ‘ReportServerTempDB.dbo.ExecutionCache’”. Apparently there is an issue renaming the reporting services tempdb as there are some internal references to stored procs and triggers that reference ReportServerTempDB. Here you have a couple of options; 1) find all references to ReportServerTempDB and change it to the renamed reporting temp db or 2)as I did rename your reporting services tempdb back to ReportServerTempDB.