After upgrading to MacOS High Sierra, Time Machine now says "Next backup: When disk is connected", even though the disk is indeed already connected. Also, automatic backups are still being performed.

I already tried doing a full reset of Time Machine* but that didn't fix it.

Time Machine screenshot

Note: As at 2019, The Pondini site has been archived to http://www.baligu.com/pondini/TM/Home.html Existing links, if you find them can be added manually, to make the above link into http://www.baligu.com/pondini/TM/A4.html

  • Yes, I've got the same issue on a 2013 Mac Pro. Interestingly, I've noted that Time Machine is doing a full backup each time and therefore the disk is full within a day. – Mark Oct 18 '17 at 19:55
  • @Mark, did this start happening to you after you upgraded to High Sierra? And does reformatting the Time Machine drive and starting the backups from scratch fix your problems? – Gary Nov 7 '17 at 1:03
  • 2
    I am seeing this error as well. I have done a clean install of High Sierra, and am using a freshly formatted disk for the backups. Time Machine gets one backup done and then switches into thinking the disk is no longer connected. If I disable and re-enable the automatic backups then it schedules another backup. The disk is connected and functional. This exact same setup worked with Sierra. – PyjamaSam Dec 6 '17 at 14:56
  • Same problem here.. – Koray Tugay May 9 '18 at 2:03

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