An external disk refuses to mount, com.apple.DiskManagement.disenter error -119930868.

I had another disc give that error (dissenter error) and this time the fsck_ext didn't show up in Activity Monitor. It wouldn't mount on the iMac - so I plugged it into a PC and formatted it ExFat from there no problem, and it now works on the Mac.

Interestingly I ran into the same issue with my new MacBook usb-c and Catalina. After I accidentally unplugged the external drive (sometimes it just removes itself, probably due to power issues) I can't mount the drive anymore. Its a portable 4TB WD drive USB3 with extfat. If I mount it on Linux on another computer it works again. It's a nasty workaround but it works for me.

I need to try in on Linux then...i have tried all options even thinking to reformat the drive and then restore the files but then i know there is a possibility that i wont be able to rescue the files or just jpg files will be rescued (i want my RAW files) paying to fix my drive is not an option.. frustrating and thinking it has something to do with Seagate wanting more cases to fix with the pixel8. Or apple not supporting seagate older drives. Just so many theories!

UPDATE FROM TODAY: APPARENTLY THE HARD DRIVE DID IT AGAIN I GOT THE 1 DISK NOT EJECTED PROPERLY

2 CHANGED STATUS TO READ ONLY

3 I WENT ON ACTIVITY MONITOR AND KILLED THE FSCK_NTFS CMD

4 WENT BACK TO DISK UTILITY AND REPAIRED.

TOOK SOME TIME BUT THE DRIVE BECAME CAME BACK TO ITS OLD STATUS TO READ AND WRITE.

It has a 15 dial free trial, but:

I'm not saying it won't solve someone's problems, but it didn't solve mine (same error encountered on ext drive like OP). It just returned: Error while mounting disk2s3: No supported file system found.

...No loss of money, but a waste of time.

Initiate Terminal mode.

At prompt, key first command and hit return/enter:

[user]$ ps -ef | grep fsck

You should see something like the following, the first three bytes from which is the PID:

  501   680   653   0  2:55PM ttys000    0:00.00 grep fsck

...Now at the prompt, you key the second command with the applicable PID:

[user]$ sudo kill 501

It might work for you (I hope it does). It did not solve my issue, and tainted disk still won't mount and I continue to see the same error as OP.

Answer: it's frustrating, but you have to wait. As per earlier responses: "[the] Drive mounts itself after it's checked for errors. It just takes time."

Here's what's going on: likely, you removed the drive manually last time instead of ejecting it (i.e. unsafely). This forces Catalina (and maybe some other OSs, I haven't checked) to run a safety check on the data in each partition on that drive once it's reinserted to make sure nothing's corrupted. If you look at the operations using CPU time on Activity Monitor (or similar), you'll see something called 'diskarbitrationd' utilizing around 50% cpu. That's the scanning process at work. If you don't see that, something else might be up. If you do... yeah, just wait. It'll mount eventually, and provided you eject safely in the future, this'll be a one-time thing.

I have a 5T WD drive that's already been formatted for a Mac, therefore EX-NTFS. Did you have any issues after downloading Tuxera? I'm having the same problems everyone else is with mounting. I get com.apple.DiskManagement.disenter error 0

Thanks for your help.

I just ran into this problem. In disk utility make certain that you're seeing all of the drive and partitions via the view button in the upper left hand portion of the screen. View all.

I had been trying first aid on the named partition and not having any luck. If you attempt first aid on the 'master boot' main part of the drive (usually has the manufacturers name, Apple, Samsung, Western Digital, etc. ), I had success bringing the drive back up that way.

I've been confused that the new OS doesn't show me all of the drive in disk utility. Let me know if that works.

You're great SAL0808!!!

I did what you suggested about downloading and installing Windows NTFS Tuxera and after the installation, the system was restarted and the external disk came to life !!!

Millions of thanks my dear, I really love you.

Hi. I did what SAL0808 suggested and after installing Windows NTFS Tuxera and once the system was restarted, the external disk returned to life and performed a time machine data backup with no problem.

mac1317's help worked when I had a disc that wouldn't mount..... now just helped my Time Machine disc that I was error checking with Disk Utility. I did this before and it took over an hour but sorted itself out and I eventually could press "done".

Not today, started, went out, came back 4 hours later and it was still "checking catalogue" (or something!)

Opened Activity Monitor and there at the top of the process list was ....... consuming a whopping 3+ Gb of memory!

Killed it, Disk Utility immediately said it had failed to verify or repair disc but at least I could get out of it!! Just checked this disc, all info still there, Time Machine working OK so no harm done.

However, that process needs looking at!

[Edited by Moderator]

I had this same issue. I purchased a Lacie d2 10TB external hard drive which is "designed for mac". Maybe it is a Catalina thing but I was getting the same error. The first time I plugged it in it mounted and the system asked if I want to use it as a Time Machine Backup drive, and thats what I wanted. The moment i Clicked "Use as Backup drive" I was prompted with the error and now it was greyed out and I run to this issue. What worked for me in the end was formatting the drive ti MacOS Extended Journaled, and now it seems to work.

I do realize that there are many people that don't want to format their drives. This issue happened to me with a brand new drive so the formatting wasn't a big issue for me since the drive was already empty. So this tip is to them who are having this issue with new drives!

I see. So on the first window, the type for the External drive is Disk. The type for the actual drive, under that is USB External Physical Volume, neither of which, I believe, is one of the types you can do a mount on in Terminal. So, it's not NTFS or FAT32, as far as I can see.

Correct me if I'm wrong, but I don't believe that data is helpful for mounting the drive or other drives like it.

I have the same problem. My system just updated to Catalina 10.15.3. My main HDD worked fine until the update completed and the computer rebooted. It is now disabled and nothing is bringing it back. Quite upset, as I am now running off of the much smaller fusion SDD, and appear to have lost access to all my data stored on the HDD.

This is a software issue, not a hardware issue.