problem with time machine after OS upgrade
I just updated my iMac from OS Maverick to High Sierra. It all seemed to go well. I was using Time Machine with no encryption on Maverick, and disconnected the external HD while I did the OS update. Then I reconnected the external HD. Time Machine gave this error message when I asked it to back up:
"Time Machine did not back up because the backup disk was previously encrypted but is no longer encrypted." But the backup disk was NOT previously encrypted so far as I know.