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Unable to mount Time Machine partition in 10.15.6

I have a Time Machine partition on an external USB HD along with two other partitions.


As of yesterday afternoon, the Time Machine partition does not mount.


The other partitions DO mount and operate normally.


What I have tried so far:


  • Mounting via Disk Utility. Result:


  • Repairing via Disk Utility. Result:


  • Erasing via Disk Utility. Result:


  • Booting in Safe Mode. Result: Nothing.


Thanks for your help

MacBook Pro 13″, macOS 10.15

Posted on Sep 11, 2020 9:04 AM

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Question marked as Top-ranking reply

Posted on Sep 12, 2020 11:51 AM

you may need to set that partition up again, which would affect the other two partitions


This is bad advice.


Following a suggestion on another thread I simply left the disk connected overnight - the issue resolved itself (after 12+ hours).


There's currently a 12-page thread (and growing) full of frustrated users also experiencing this issue.

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2 replies
Question marked as Top-ranking reply

Sep 12, 2020 11:51 AM in response to SnickZ.

you may need to set that partition up again, which would affect the other two partitions


This is bad advice.


Following a suggestion on another thread I simply left the disk connected overnight - the issue resolved itself (after 12+ hours).


There's currently a 12-page thread (and growing) full of frustrated users also experiencing this issue.

Sep 12, 2020 10:09 AM in response to saddlemeyer

Hello saddlemeyer,


Thank you for using Apple Support Communities.


We see that your Time Machine partition is not mounting and the error messages from Disk Utility. It appears that the partition for Time Machine has become damaged and is not repairable. The error when you try to erase the partition is indicating something with the identification blocks for that partition and you may need to set that partition up again, which would affect the other two partitions.


You will want to backup the data on those two partitions first and then take a look at the following support article to partition the disk.


Partition a physical disk in Disk Utility on Mac - Apple Support


Best regards.

Unable to mount Time Machine partition in 10.15.6

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