Can't get inheriting TM to work (Big Sur)

Solution 1:

I had the same issue.
Seems to me that the -a option of tmutils is broken in Big Sur (11.2.1).

However, instead of letting tmutils perform the association on all volume stores:

sudo tmutil associatedisk -a "/Volumes/Macintosh HD" "/Volumes/Time Machine Backup/Backups.backupdb/Christian Fischer’s iMac/Latest/Macintosh HD"

you can do the association for each volume store yourself:

for f in "/Volumes/Time Machine Backup/Backups.backupdb/Christian Fischer’s iMac/"*; do if [[ -d "$f" ]]; then sudo tmutil associatedisk / "$f/Macintosh HD"; fi; done

This worked for me like a charm ;-)