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Time Machine could not back up the disk “Macintosh HD - Data” because a snapshot of the disk could not be created.

This is the message that I received on my iMac (late 2015) with one TB fusion drive. I also used another empty external 8TB hard drive withe the same result.


Right now, Time Machine is not creating new backups so the problem has to do with accessing the iMac hard drive??


iMac 27″, macOS 11.5

Posted on Aug 9, 2021 4:26 PM

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Question marked as Top-ranking reply

Posted on Aug 9, 2021 4:30 PM

Lets try some basics first, I would recommend restarting the computer in Safe Mode with no wired peripherals (including the Time Machine drive) connected. Then restart normally, connect the Time Machine drive and test it.


Instructions for a Safe Mode start are in Use Safe Mode to isolate issues with your Mac

2 replies
Question marked as Top-ranking reply

Aug 9, 2021 4:30 PM in response to rayfromsperryville

Lets try some basics first, I would recommend restarting the computer in Safe Mode with no wired peripherals (including the Time Machine drive) connected. Then restart normally, connect the Time Machine drive and test it.


Instructions for a Safe Mode start are in Use Safe Mode to isolate issues with your Mac

Time Machine could not back up the disk “Macintosh HD - Data” because a snapshot of the disk could not be created.

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