I have (well, had) a Late 2013 MacBook Pro running Big Sur backing up via Time Machine to a Time Capsule. That MacBook died a sudden and horrible death with no chance of ever booting again.
In an attempt to restore files from the above backup, I used Migration Assistant on a new M1 MacBook Pro running Monterey. Migration Assistant tells me "Backup in use, try again later." The same Time Capsule also houses a MacBook Air backup which is available as a source for restoring files --- unless that MacBook Air is currently backing up via Time Machine, in which case it too causes "Backup in use, try again later".
So it seems that the Late 2013 MacBook Pro might've died right in the middle of a Time Machine operation, leaving the Time Capsule's sparse bundle in some sort of "I'm busy dealing with a backup" state.
Is there a way I can do something to the Time Capsule's files to force it out of the "Backup in use" state?
More info: The MacBook Pro backup's sparse disk image bundle is named with a .backupbundle suffix and the MacBook Air's is .sparsebundle -- not sure why or if it's even relevant.
Even more info: I have not tried rebooting the Time Capsule for two reasons: (a) that MacBook Air is still backing up and (b) I'm afraid pulling the plug will create an even bigger mess with the MacBook Pro's backup.