I recently ported an SSRS instance to a freshly minted virtual machine.
As usual I went through the normal SSRS configurations and everything looked happy.
As part of the process I restored the reporting services databases to the new SSRS database instance.
Apparently I didn’t follow my own instructions Migrate SSRS from SQL Server 2008R2 to 2014.
When I attempted to go to the Report Manager URL I got the error message: The report server installation is not initialized. (rsReportServerNotActivated).
There are probably several reasons why this message could be presented but it my case it was just a matter of backing up the encryption key on the source SSRS instance and restoring it to the new SSRS instance.
Without that key, SSRS is unable to read from its own databases.
Simple stuff, but not obvious from the error message.
Stay curious; keep learning.