Time Machine snapshot could not be created for the disk "%@"
I just upgraded my iMac (Retina 5K, 27-inch, Late 2014) to Big Sur. All went well, except Time Machine now will no longer create a backup.
I get the error: "Time Machine could not back up the disk "%@" because a snapshot of the disk could not be created."
I have about 87GB free on my single 1TB Fusion Drive.
After some googling, I have tried:
a. Run Disk Utility First Aid on the Fusion Drive (and again on the contained volumes - no issues).
b. Deleted old local snapshots - to free up space (tmutil listlocalsnapshots / etc.).
c. Confirmed I could manually create a new snapshot (tmutil snapshot).
d. Tried using a new Time Machine backup disk (no difference, as I assume the issue is happening before it actually backs up to the backup disk itself).
I suspect the key to the problem is the disk "%@" that Time Machine is apparnetly trying to create a snapshot of.
What is disk "%@" ? It sounds like a bogus disk reference? (which might explain why a snapshot could not be created).
I'm not sure what to try next?
