iCloud password not accepted
I keep getting a message that my iCloud access has been disconnected. When I go to my iCloud preferences and input my (known good) password, I get an error message saying an unknown error has occurred - and that's as far as I can get. Yet when I sign in to the Apple discussions with the same password, everything is OK.
What is likely causing this iCloud access problem, and how can I get around it?
Thanks.
Paul.
iMac 21.5", macOS 10.13