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Time Machine Backup Fails

recently, perhaps since going to Catalina, my Time Machine fails to back up. Details say that the OS was 'unable to complete back-up. An error occured while creating the back-up folder".


Does anybody else have this problem and what is the solution?

iMac Line (2012 and Later)

Posted on May 29, 2020 1:29 AM

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Posted on May 29, 2020 8:25 AM

If you can't back up or restore your Mac using Time Machine suggests running Disk Utility's First Aid:


  • To check an external drive connected to your Mac, open Disk Utility from the Utilities folder of your Applications folder. Then use the First Aid feature in Disk Utility to verify your disk. Do this for your startup disk as well.


Repair a storage device in Disk Utility on Mac - Apple Support explains how to use First Aid.


I added the boldface for emphasis because it's frequently overlooked. To "repair" the startup disk (source) requires restarting your Mac in Recovery mode: Restart your computer in macOS Recovery.

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Question marked as Best reply

May 29, 2020 8:25 AM in response to art Harris

If you can't back up or restore your Mac using Time Machine suggests running Disk Utility's First Aid:


  • To check an external drive connected to your Mac, open Disk Utility from the Utilities folder of your Applications folder. Then use the First Aid feature in Disk Utility to verify your disk. Do this for your startup disk as well.


Repair a storage device in Disk Utility on Mac - Apple Support explains how to use First Aid.


I added the boldface for emphasis because it's frequently overlooked. To "repair" the startup disk (source) requires restarting your Mac in Recovery mode: Restart your computer in macOS Recovery.

May 30, 2020 2:16 AM in response to John Galt

Thank you, but I had already done these things. It seems that there is a problem with the drive as it cannot be unmounted. The OS tells me that something is using it but I can't find what.I can't even erase it. I have disconnected it (it was part of a WD double array and had been set up mirrtored; WD utility just gives query marks) and will try to erase the disc in a separate. holder.

Time Machine Backup Fails

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