Solved by this. Can't post as answer due to low reputation on this network site.
- on the server (in my case the iMac) in the settings --> sharing tab, disable file sharing (no need to reboot or whatever)
- on the "client" side (the machine from which you want to access the external TM drive mounted on the server) force restart the finder app (via "xefxa3xbf--> Force Quit" menu
- re-activate the file sharing on the server again.
I have a Mac Mini on my network with an external hard drive mounted on it. I use this external drive for Time Machine for a couple computers.
All was well until today, when I got a new Mac Mini. I migrated all my stuff over to the new machine, mounted my backup disk and tried to add it as the Time Machine backup drive in my Macbook Pro. I get the following error:
Time Machine canxe2x80x99t connect to the backup disk.
The operation couldnxe2x80x99t be completed. (OSStatus error 13.)
I've tried a number of troubleshooting tips. Restarted both machines, restarted the external enclosure, even reformatted the backups drive (nothing important was lost... I hope).
As a possible hint to a root problem,
Finder -> Go -> Network -> [Computer] -> Backups raises an error as well:
The operation canxe2x80x99t be completed because the original item for xe2x80x9cBackupsxe2x80x9d canxe2x80x99t be found.
Both machines are running macOS 10.15.