Macbook Pro won't mount External Hardrives

I have had this issue for years and only just found a solution.

My issue was that if I accidentally unplugged a disk or restarted before clicking "eject", the disk would then become unusable until I connected it to a non macOS device and did a scan disk utility.

The solution I have just found is as follows...

Open up the terminal and run:

diskutil unmountDisk /dev/disk2

diskutil eject /dev/disk2

Then, unplug the disk and re-connect it. It should appear.

Hope this helps.

I suspect it’s having issues loading the NTFS kernel extension (kext). Can you try rebooting in safe mode once:

https://support.apple.com/en-us/HT201262

After you booted I safe mode, just reboot again normally. This will clear some caches and might help.

Have you tried to do a "First Aid" on that volume in Disk Utility? What does it say (post the details of this)? If you've already tried this and no problems found, try the following...

Try mounting from command line using "mount" command. Need to know a couple of things:

device name - get this from a "diskutil list" command -- its something like /dev/disk3s3 or whatever

is the partition slice for the problematic drive

file system type - probably HFS+ -- this info will also be shown in the "diskutil list" output but the

actual string is a bit different

So a possible mount command would be (sudo commands will ask for your account password and assume it to be an "admin" type account) -- this is only an example as your situation needs to reflect your disk name and partition and the first "mkdir" command should be a folder that does not already exist:

sudo mkdir /Volumes/Seagate

sudo mount -t hfs /dev/disk3s2 /Volumes/Seagate

When you try the mount command you will see some sort of error -- then we can try and figure out what the problem might be.

Good luck...

You have several issues:

The Seagate volume is an NTFS volume (used for Windows systems usually) -- you need special software to check/mount those types of volumes, e.g. Paragon or others. If you have this software then the mount command would need to have "-t ntfs" instead of "-t hfs" I think (check with your software provider).

You need a space between the "/dev/disk1s2" and the /Volumes/Seagate... and you also need to enclose the /Volumes/Seagate... in quotes or escape the space character in the volume name -- should be something like "/dev/disk2/Volumes/Seagate Backup Plus Drive" and you also need to make the folder name in "mkdir" command using /Volumes match. Are you certain it's the full name "Seagate Backup Plus Drive" and not just "Seagate"?

What software are you using to backup to this NTFS volume? Did the "Seagate" drive come with software so that you could use it on Mac's?? Unless you want to use this drive on another Windows system you might want to think about formatting it as HFS+ (since that is native to Mac systems but Windows systems would have a problem reading it without third party software) but realize you will loose everything on it when you do this. Is there anything on the drive at all you wish to preserve?

Also please do this in a Terminal window before doing anything else:

diskutil list

and also do

df -kt

so we can see some important information. Also keep asking questions before doing anything that cannot be undone so you understand the issues.

Good luck...

Yes, that should work. But I was wondering why your other Mac is able to mount the NTFS volume with no extra software installed, so I dug a little deeper...

Turns out my initial response was actually incorrect / outdated: The later versions of macOS can read and even write to NTFS volumes natively. Writing is disabled by default and not supported by Apple should you choose to enable it, but reading is actually enabled by default.

Since pressing mount in Disk Utility doesn't seem to do anything: can you open the Console app and try mounting the volume again? Then search for "mount" in Console. Maybe you'll see an error message there that will give some clue.

No, they didn't remove them - still there.

Something isn't correct about that mount command you entered in Terminal, that's why it's showing you the usage.

The Console app is actually a log viewer. The easiest way to open it is to search for Console in Spotlight. Once you open it, you should see the stream of log messages going by. Try to mount the drive using Disk Utility - not Terminal - with Console open and then search Console for "mount". It should show you something.

How is it formatted?