Site attempting to fallback from Sysview Performance Management for Db2 for z/OS (IDB2) r19 to r18 and the data collector failed with the following errors:
DBG21001I 16:07:47 HISTORY: INITIALIZATION STARTING
DBG21023E 16:07:47 HISTORY: FILE HSTSTATS INVALID HISTORY FILE.
DBG36017E 16:07:47 OPEN FAILED FOR DDNAME HSTSTATS
DBG11017I 16:07:47 ESTAE EXIT IN NUHSTLOG INVOKED BY ABEND
ABEND CODE IS 04138000 - EC PSW AT ABEND IS 070C2001 9651A600 - PRIMARY MODE, SUPR STATE, 64-BIT MODE, PASID/SASID=00070118, TCB
ILC, INTERRUPT CODE 0002000D - TRANSLATE EXCEP 7F473400
Once you upgrade IDB2 from a lower to the higher release and you take with you the history files of the lower release
and start writing to them in the higher release, you cannot use them if you fallback to the lower level again.
If you try to use them again with the lower level data collector, you will get the following error:
DBG21023E 16:07:47 HISTORY: FILE HSTSTATS INVALID HISTORY FILE
DBG36017E 16:07:47 OPEN FAILED FOR DDNAME HSTSTATS
The best option will be to create a new r18 files if you want to fall back.