I just upgraded one of a pair of fail over AF Servers to PI AF Services 2017 R2. One upgraded without issues and no errors when opening or navigating databases. The other however gives me an error popup stating "Value cannot be null. Parameter name: source". Here is a screenshot:
I get the same error for each AF database, and this condition only occurs on this AF Server. The fail over pair sources the same SQL PIFD database. I click [OK] and am apparently able to perform all actions normally. Event logs are not revealing the issue. I have already un-installed, and then re-installed, with the same error before and after.