[Upgrade with DBUA + REMOTE_LISTENER with unresolvable SCAN => Fail] & [crsctl “-unsupported” supports you!]

I played with some troubleshooting tasks during database upgrade and stumbled upon some – how can I describe it? – a new findings for me. I have following environment: 2-node RAC environment with Grid Infrastructure version 12.1.0.2 1 RAC database still running on 11GR2 (11.2.0.3) Note: the parameter REMOTE_LISTENER is empty Scenario: That database should ...