Why do I get message: Time Machine couldn’t complete the backup to “WD 4TB Time Machine”.

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Level 1

9 points

Why do I get message: Time Machine couldn’t complete the backup to “WD 4TB Time Machine”.

iMac running Mac OS Big Sur 11.6. I used this drive for Time Machine for months then suddenly got the message in the title. Disk Utility failed to fix it. I bought a new external drive. It worked twice, then got the same message. Disk Utility failed to fix it. I used Disk Utility to erase the frist drive. Time Machine worked once. Next time I got the same message. Disk Utility failed to fix it. I have not seen any likely solutions posted so far. Help?

iMac 27″, macOS 11.2

Posted on Oct 10, 2021 8:36 AM

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Answer 1

FrancisOscar Author

Level 1

9 points

Oct 10, 2021 11:14 AM in response to ku4hx

The new one is a USB powered LaCie 5TB which came with its own short cable. Time Machine backed up to it once or twice before giving me the error message. The older drive is a 4TB WD, not USB powered, which worked for some months before giving the error message. Both were only used for Time Machine.

On each, Disk Utility fails to repair. Both are APFS volumes.

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Answer 2

FrancisOscar Author

Level 1

9 points

Oct 10, 2021 11:45 AM in response to FrancisOscar

When I run Disk Utiity, here is what I get:

Repairing file system.

Volume was successfully unmounted.

Performing fsck_apfs -y -x /dev/rdisk5s2

error: container /dev/rdisk5 is mounted.

File system check exit code is 65.

Restoring the original state found as mounted.

File system verify or repair failed. : (-69845)

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Answer 3

Old Toad

Level 10

208,003 points

Oct 10, 2021 11:52 AM in response to FrancisOscar

Have you run Disk Utility's First Aid on the boot drive (it'll have to be done while booted into the Recovery volume - boot with the Command + R keys held down)?

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