we have upgraded confluence to version 9.2.2 and we have started to see instability on our site, we have seen Java Heap memory issues, this java thing we have bumped the value to 2048, but we need to upgrade our database from version 13.8 to version 15 at least, we have tried to do this on our testing environment but failed many times we had to restore our test machine from backups, any help would be very good, thanks in advance.