After upgrading to Catalina, it asks me to update my Apple ID settings. On entering the password it would cycle through several error messages and requested input with no success. Keychain choice was not in my iCloud backup list. I did manage to partially disconnect from iCloud but that did not change the issue. A couple of other oddities. Apple mail would not sync with some previously used accounts. In fact when I tried to send an email from my iCloud account, the email send window kept flashing up on the screen. Another oddity was that I couldn't add a CD to my music library, the list of songs on the CD would flash up then disappear, similar to the email issue. On login the sharing window of System Preferences would automatically open. Each time Safari was started it would open a login page for Outlook365. To use Parallels I had to restore the virtual machine from Time Machine before it could be accessed.
Soooooo.....my solution was to create a new user account with administration capabilities. Lo and behold, it seems too have worked. I can authenticate to iCloud. So far it seems to be fine. Now I need to move my folders to this new user along with Safari bookmarks. Passwords I will due by hand although there are instructions available for moving the key chain data to the new environment. This is relatively easy as I keep a log of them which is usually ;-) up to date.
As to the cause of this, I have no idea. It should be noted that my virtual machine hd space is over 40Gig.
Hope this helps some one.