Mac – Fixing Time Machine Backup Broken by Deleting Most Recent Backup with tmutil

Not a real answer, more a workaround to have your backups automatically despite this bug. That worked for me (see this answer of my own question).

Open a command line and say tmutil destinationinfo. Copy the ID you see in the ID line (a long suite of alphanumerical characters and -'s).

Now type tmutil startbackup -d TheID replacing TheID by the ID you just noted before (so something like tmutil startbackup -d 11326F32-D5BA-4FE8-83FB-E9CBD8F6FF2D but with an other ID). Open Time Machine Preferences and check if the backup is running. You may have to wait a few seconds before you see anything.

If that works, you can add it to your crontab so it is automatically run manually every hour (sounds contradictory?). Type crontab -e on the command line to edit your cron jobs, and add the following line in it:

0 * * * * tmutil startbackup -d TheID

again replacing TheID by the ID of your backup. Next hour check if anything is happening. You can replace the leading 0 by the minute you want it to be run.

Not completely sure if it will works since I don't know when the snapshot was taken (before or after an update). You can go into your system preferences, spotlight, privacy tab, add your hard drive, reboot, remove the hard drive from spotlight and let the spotlight re-index (this can take a while). Try going into time machine again.

Updates have messed up Time Machine when doing a clean install and upgrade for quite a few people and this was the fix.