Yesterday, I downloaded and installed the above version for the first time (on Windows Server 2019).
First problem - the download page lists .NET Framework 4.7 or later as a prerequisite, but the install program requires 4.8. That was easily solved.
The second problem cost me a lot of time. SSRS uses a temporary directory <installdir>\SSRS\ReportServer\RSTempFiles, but the install program did not grant modify rights to this directory, so impossible to create reports or data sources either from the web interface or by deploying a report.
I was trying to do an in-place upgrade from SQL 2012 to 2019. I put the failed migration to one side, upgraded the database without problems and after several tries, deinstalled SSRS, deleted the databases and reinstalled SSRS from scratch.
So I suspect the problem is in the latest update and not related to migration.
I was unable to check Windows Update before installing because my WSUS database is on the server in question!
