Error message DBG55166E TESTVER does not match after the Sysview Performance Management Option for Db2 for z/OS (IDB2)
upgrade to release 20.0 working with the Remote Access Facility (RAF) to connect a remote data collector.
Sysview for Db2 release 20.0 unlike previous versions actually tests the TESTVER value when RAF connection is established.
You need to adjust the configuration with TESTVER=R20 in the IDUIPRMS member for the User Interface.
Probably you have to review TESTVER parameter in PGM=IDB2UIFI program to unload the History files or in PGM=IUIBATCH
program batch user interface, now you should have TESTVER=R20 which is the default value for the Sysview for Db2 Release 20.0.