unknown error occured

I upgraded to Catalina. I now get "an unknown error has occurred" message when trying to log in to iCloud using my Apple ID. I have exited iCloud, rebooted, but to no avail. I have removed keychain access files and rebooted. I have removed all ids files and authtokens. Still getting the error message. I have rebooted in safe mode. What do I do next short of throwing this out the window?