In a previous article I described how to setup an encrypted TimeMachine Backup. That used to work fine until a few month ago. I noticed back then that the automatic scheduled backup can’t seem to mount the encrypted volume anymore. However when I click on the TimeMachine icon in the menu bar and select “Backup Now” it will work just fine.
I couldn’t figure out what was the root cause of this behavior. But at least I found a workaround now. There is a free tool to change the schedule of the TimeMachine backups called TimeMachineEditor. This uses an alternate scheduling mechanism to trigger regular backups. I set the schedule to be 1h and it works just fine now.