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'Time Machine couldn’t complete the backup' error after power outage

My Time Machine hasn't been able to back up for 3 weeks. I had a power outage back then and ever since I get the following error:


The backup disk could not be found. Make sure the backup disk is connected or select a different backup disk.


I've tried restarting my iMac, relaunching Finder, ejecting the drive physically and virtually but nothing has worked.

iMac 27″ 5K, macOS 11.0

Posted on Dec 28, 2020 12:16 AM

Reply
Question marked as Top-ranking reply

Posted on Dec 29, 2020 7:57 PM

Remove the disk from Time Machine.

  • Click Select Disk
  • Select that drive from the list
  • Click remove


Open Disk Utility

  • Select "Show All Devices" from the View button popup menu
  • Select the drive device name in the disk list
  • Click Erase button in Toolbar
  • Select GUID partition map, APFS Format, and name the drive
  • Click Erase


When it is done and mounted, Time Machine may ask if you want to use it as a backup disk. If so, click yes.

If not, Add the drive to Time Machine.

8 replies
Question marked as Top-ranking reply

Dec 29, 2020 7:57 PM in response to erahi

Remove the disk from Time Machine.

  • Click Select Disk
  • Select that drive from the list
  • Click remove


Open Disk Utility

  • Select "Show All Devices" from the View button popup menu
  • Select the drive device name in the disk list
  • Click Erase button in Toolbar
  • Select GUID partition map, APFS Format, and name the drive
  • Click Erase


When it is done and mounted, Time Machine may ask if you want to use it as a backup disk. If so, click yes.

If not, Add the drive to Time Machine.

'Time Machine couldn’t complete the backup' error after power outage

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