Encountering DBG55166E TESTVER does not match message in Sysview Performance Management Option for Db2 for z/OS (IDB2) PickDB2 option.
The TESTVER parameter is commented out in all parameter data set members IDDCPRMS and IDUIPRMS so it should be defaulting to the
value for the current release TESTVER=R20.
Problem was in the IDUIPRMS parameters and the RAF connection. Sysview for Db2 Release 20.0 unlike previous versions actually tests
the TESTVER value when RAF connection is established. Need to adjust the configuration with TESTVER=R20 in the IDUIPRMS
member for the User Interface, assuming you have not updated the TESTVER parameter IDDCPRMS member and it defaults to TESTVER=R20.