macos Majove cannot read disk from Big Sur

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macos Majove cannot read disk from Big Sur

I have a disk from another machine that was running big sur. I went back to my box that has mojave. I attached the big sur drive to the mojave box and it says it cannot read the disk. It says unsupported format.

Is there a way to read it so I can copy files from it? Th update and data containers mount but not the main part of the disk. The data part of the disk is not readable. No perms. It has the red minus pic on the folders. I do not have access to the big sur box anymore.

I did try to use disk utility to mount all devices ;but the main part of the disk still does not mount.

Posted on Jan 19, 2021 12:48 PM

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Answer 1

Top-ranking reply

Eau Rouge

Level 8

42,596 points

Jan 20, 2021 4:56 AM in response to TRON3030

With the Big Sur disk connected to your Mojave mac,

make sure the Big Sur disks icon is displayed on the Desktop.

Highlight the Big Sur disk and press Command and i

this will bring up the info panel

at the bottom click on Sharing & Permissions.

Click the plus button and add your user name to the list,

make sure the permissions are set to Read & Write then

click the gear icon with the downward pointing arrow and click

on Apply to enclosed items.

After a few minutes the no entry sign will disappear from the folders.

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Answer 2

PRP_53

Level 10

91,663 points

Jan 20, 2021 4:03 AM in response to TRON3030

The issue might be the External Drive with Big Sur is formatted as APFS which the Box machine running Mojave does not understand this system formatting.

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Answer 3

TRON3030 Author

Level 1

17 points

Jan 20, 2021 4:47 AM in response to TRON3030

correct. I was posting to see if there is a way to still mount it. I may check for APFS software; but was wondering if there was another way inside mojave to mount it.

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Answer 4

Eau Rouge

Level 8

42,596 points

Jan 20, 2021 4:48 AM in response to PRP_53

Mojave is APFS native that is not the issue.

The Big Sur drive is owned by the owner of the Big Sur install.

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Answer 5

TRON3030 Author

Level 1

17 points

Jan 20, 2021 5:06 AM in response to Eau Rouge

thanks for the quick reply. i will test this out.

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Answer 6

TRON3030 Author

Level 1

17 points

Jan 20, 2021 5:08 AM in response to TRON3030

i am running a back up right now and will test after.

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Answer 7

TRON3030 Author

Level 1

17 points

Jan 20, 2021 8:33 AM in response to Eau Rouge

thanks. that worked. it did not give perms for the whole disk at once; but I was still able to drill down to the folders I wanted to get to like docs, downloads etc. thanks again.

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Answer 8

TRON3030 Author

Level 1

17 points

Jan 20, 2021 8:35 AM in response to TRON3030

oh , i see now. i did not click up for all enclosed items. i will try that as well.

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macos Majove cannot read disk from Big Sur

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