Greetings to you! For now; hope you are all healthy !? To my question: 1) Who knows this message (hard disk utility first aid) - Warning: MT mapping is not completely referenced? Now had no (or only the usual Catalina) problems, but occasionally run first aid over it. This message comes at "Container disc2" at the end of the check. The same when checking from "Fusion Drive". The same message comes. With Macintosh HD 1 + 2 data - does this message not appear? Couldn't find much about it on the net, tried some suggestions https://discussions.apple.com/thread/251159425 but didn't do anything. Ne reinstall. I still did before I don't know what that means - I have backups with TM anyway. That with the reinstall. was a recommendation to fix the problem - whatever the consequences could be ....? 2) Did someone check that with "first aid"? 3) If so. Does this message come from Erste H. only for "Container disc2" and "Fusion Drive"? I found that after Catalina installation. Clean installation didn't help either? I was unfortunately not able to load a ScreenShot ??