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Can't mount or format external drive with APFS volume

I have an external drive that previously had worked fine but now is unable to mount. Any time I try to mount it in Disk Utility I get:


"Could not mount “disk2s2”. (com.apple.DiskManagement.disenter error -119930868.)"


I have ran First Aid and got:


"Running First Aid on “” (disk2s2)


Repairing storage system

Performing fsck_apfs -y -x /dev/disk2s2

Checking the container superblock.

Checking the space manager.

Checking the space manager free queue trees.

Checking the object map.

Checking volume.

Checking the APFS volume superblock.

Checking the object map.

Checking the snapshot metadata tree.

Checking the snapshot metadata.

Checking the extent ref tree.

error: btn: invalid key order (0) oid 9951686 / oxid 0 / level 1 / flags 0x0

previous key: 0x200000002d507b53


current key: 0x200000002bb21561


next key: 0x200000002bb38e15


Extent ref tree is invalid.

The volume /dev/disk2s2 could not be verified completely.

Storage system check exit code is 0.


Operation successful."


When I try to erase the drive in terminal I get this:


"Started erase on disk2

Unmounting disk

Error: -69877: Couldn't open device"


I really don't mind losing the data, I'd just like the drive usable again.


MacBook Pro 13″, OS X 10.11

Posted on Jul 22, 2021 8:37 AM

Reply
Question marked as Top-ranking reply

Posted on Jul 22, 2021 5:26 PM

You need to erase the physical drive instead of the Container.


Beginning with macOS 10.13 the physical drives are hidden from view by default within the Disk Utility GUI interface. So with Disk Utility you need to click "View" and select "Show All Devices" so that the physical drives appear on the left pane of Disk Utility. If you still cannot erase the drive when selecting the physical drive, then write zeroes to the beginning of the physical drive using "dd" so that the partition table and early part of the file system is overwritten. Sometimes Disk Utility just cannot handle drives which may have unexpected or corrupted layouts. Usually I only have to do this with external drives especially USB sticks especially ones where I "burn" an ISO file to it.


It is also possible the physical drive may be failing. You can try running the Apple Diagnostics to see if any hardware issues are detected, however, the diagnostics don't detect a lot of drive failures so this is only useful if the diagnostics fail. If you can boot an external macOS drive, then you can check the health of the internal drive by running DriveDx and posting the report here using the "Additional Text" icon which looks like a piece of paper. DriveDx does a good job interpreting the health of a hard drive, but can give false failures when interpreting the health of an SSD. If you have a non-USB-C Mac, then I can provide instructions for checking the health of the drive using a bootable Linux USB stick if you are interested.


Edit: I forgot you mentioned external drive so you can use DriveDx, but it will require installing a special USB driver in order to access the health information of the drive over USB. However, even with the special USB driver some external drives won't allow access to the health information on the external drive.


You may also want to try using another USB cable. Also connect the external drive directly to the laptop as any adapters, docks, and hubs may be causing problems. If you must use an adapter, then try using another one especially a different brand. Also try using other ports especially on the other side of the laptop.


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2 replies
Question marked as Top-ranking reply

Jul 22, 2021 5:26 PM in response to Jaythomasbrooks

You need to erase the physical drive instead of the Container.


Beginning with macOS 10.13 the physical drives are hidden from view by default within the Disk Utility GUI interface. So with Disk Utility you need to click "View" and select "Show All Devices" so that the physical drives appear on the left pane of Disk Utility. If you still cannot erase the drive when selecting the physical drive, then write zeroes to the beginning of the physical drive using "dd" so that the partition table and early part of the file system is overwritten. Sometimes Disk Utility just cannot handle drives which may have unexpected or corrupted layouts. Usually I only have to do this with external drives especially USB sticks especially ones where I "burn" an ISO file to it.


It is also possible the physical drive may be failing. You can try running the Apple Diagnostics to see if any hardware issues are detected, however, the diagnostics don't detect a lot of drive failures so this is only useful if the diagnostics fail. If you can boot an external macOS drive, then you can check the health of the internal drive by running DriveDx and posting the report here using the "Additional Text" icon which looks like a piece of paper. DriveDx does a good job interpreting the health of a hard drive, but can give false failures when interpreting the health of an SSD. If you have a non-USB-C Mac, then I can provide instructions for checking the health of the drive using a bootable Linux USB stick if you are interested.


Edit: I forgot you mentioned external drive so you can use DriveDx, but it will require installing a special USB driver in order to access the health information of the drive over USB. However, even with the special USB driver some external drives won't allow access to the health information on the external drive.


You may also want to try using another USB cable. Also connect the external drive directly to the laptop as any adapters, docks, and hubs may be causing problems. If you must use an adapter, then try using another one especially a different brand. Also try using other ports especially on the other side of the laptop.


Can't mount or format external drive with APFS volume

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