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I have an external NTFS hard drive that I am trying to mount on my Mac. It was working fine until I inadvertedly unplugged it before properly ejecting.

I can see the disk with diskutil:

/dev/disk3 (external, physical):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:     FDisk_partition_scheme                        *2.0 TB     disk3
   1:               Windows_NTFS ⁨disk_name               2.0 TB     disk3s1

I tried the following command with the (disapointing) following outputs:

$ diskutil mount /dev/disk3
Volume on disk3 timed out waiting to mount

$ diskutil verifyDisk /dev/disk3
Unable to verify this whole disk: A GUID Partition Table (GPT) partitioning scheme is required (-69773)

N.B. I have another USB drive that works fine with a Windows_NTFS partition. Moreover, the disk mounts without any problem on a Windows computer, meaning I can see the content of the hard drive without problems.

EDIT

I ran chkdsk with the following output:

PS D:\> chkdsk
The type of the file system is exFAT.
Access is denied.

The volume is in use by another process. Chkdsk
might report errors when no corruption is present.
Volume Serial Number is ****-****
Windows is verifying files and folders...
Volume label is name_of_drive.
Windows found errors on the disk, but will not fix them
because disk checking was run without the /F (fix) parameter.
Corruption was found while examining the volume bitmap.
File and folder verification is complete.

Windows has checked the file system and found problems.
Run CHKDSK with the /F (fix) option to correct these.

1953247232 KB total disk space.
1588895104 KB in 3138236 files.
    674688 KB in 1671 indexes.
         0 KB in bad sectors.
      2048 KB in use by the system.
 363675392 KB available on disk.

    131072 bytes in each allocation unit.
  15259744 total allocation units on disk.
   2841214 allocation units available on disk.

I then ran the following chkdsk /F with the following output:

PS D:\> chkdsk /F
The type of the file system is exFAT.
Cannot lock current drive.

Chkdsk cannot run because the volume is in use by another
process.  Chkdsk may run if this volume is dismounted first.
ALL OPENED HANDLES TO THIS VOLUME WOULD THEN BE INVALID.
Would you like to force a dismount on this volume? (Y/N) y
Volume dismounted.  All opened handles to this volume are now invalid.
Volume Serial Number is ****-****
Windows is verifying files and folders...
Volume label is name_of_drive.
Corruption was found while examining the volume bitmap.
File and folder verification is complete.

Windows has made corrections to the file system.
No further action is required.

1953247232 KB total disk space.
1588895616 KB in 3138237 files.
    674816 KB in 1672 indexes.
         0 KB in bad sectors.
      2048 KB in use by the system.
 363674752 KB available on disk.

    131072 bytes in each allocation unit.
  15259744 total allocation units on disk.
   2841209 allocation units available on disk.

It worked (The disk could finally be mounted in my Mac)!!

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  • Not properly ejecting drives can cause terminal errors. You may want to check out the answers here: apple.stackexchange.com/q/293390/237687. But you might end up having to reformat, partition and restore the data from your backup.
    – Solar Mike
    Commented Sep 5, 2022 at 12:25
  • 1
    What happens if you run chkdsk on the Windows PC? Does that find any errors or make it mountable on the Mac? Commented Sep 5, 2022 at 22:08
  • thanks for your comment @SteveChambers. I will try that today. Shall I write this command in powershell (and if yes what would the be pattern to use as I am not a regular windows user)? In the meantime: I have now two additional external disk that were properly working and suddenly are not working anymore!
    – ecjb
    Commented Sep 7, 2022 at 8:15
  • Ok @SteveChambers , I tried the command chkdsk on Powershell and I got the following: Windows cannot check a disk attached through a network. I suppose this is because this is the PC of my workplace which is attached to a central server
    – ecjb
    Commented Sep 7, 2022 at 12:41
  • By "external drive I am trying to mount on my Mac" I assumed a USB (or some such) drive plugged directly into your Mac. If it is a network drive that is VERY different and troubleshooting would start on the device it is shared from (Server, NAS, etc...) Commented Sep 7, 2022 at 12:48

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