If like me you come across the error below after navigating to http://reportsystem/reportserver
The version of the report server database is either in a format that is not valid, or it cannot be read. The found version is '163'. The expected version is '162'. (rsInvalidReportServerDatabase).Luckily this was in a DEV environment and was part of our patching cycle to test SQL Server 2012 SP2+CU5.
As we already knew changes were made to the SQL Servers in terms of patching there was a good chance it was related ;-)
Although this MSDN wasn't the exact problem, it did lead me to a simple solution in the end.
As we host separate SSRS servers to the database it was notices that the SSRS instance hadn't been patched. Normally this doesn't cause issues within reporting server reviewing the MSDN pointed me in the right direction due to MS changing the DB versions within this patch.
Therefore patching the Reporting Services instance to 2012 SP2 + CU5 resolved the issues.