DISK UTILITY WON’T MOUNT ERROR WHEN TRYING TO ERASE

Most of the items shown in the output including what has scrolled off the top of the screen are just virtual volumes for the macOS installer which should already be mounted if they are appearing in the list. Usually the physical drives will appear as the first items in the output which has scrolled off the top of the screen. With some later versions of macOS, it is possible to limit the output to just the internal drives & volumes:

diskutil  list  internal

The second mistake is the command being used to attempt mounting of the volumes. You are not using the correct drive identifier. Usually it is easier to just use the "diskutil" command to mount volumes anyway as you don't need to specify the file system type.

This is just an example on how to mount a volume since it is shown in the screenshot, but this won't actually work since this is a disk image which has already been automatically mounted by the macOS installer. You would need to use an unmounted volume associated with a physical disk for these options to actually work. The "diskutil" command will automatically create a mount point in "/Volumes". After unmounting the volume, "diskutil" will automatically remove the folder for the mount point.

diskutil  mount  disk20

To be able to use the "mount" command, you must already have a folder available to use as a mount point. If you don't have such a folder, then you must first create one.

mkdir  /Volumes/mountpoint

mount  -t  hfs  /dev/disk20  /Volumes/mountpoint

FYI, I'm making an assumption that the file system on disk20 is MacOS Extended (aka HFS or HFS+). I am not certain if "hfs" is the correct file system type either as I don't have time to research the specifics, but the command shows basically what is needed. The "mount" command requires the "/dev/diskX" designation while the "diskutil" command can use it as well, but "diskutil" can also work without the "/dev/" part.

FYI, You can view all mounted volumes by using the following command:

mount



You need to take a step back.

What is it you're trying to do?

From the description it isn't clear. Are you trying to erase this disk? wipe the entire machine? something else?

Additionally, the volume in question appears to be a disk image, not a physical disk... by definition, a disk image appears as a file on a larger file system, so erasing the enclosing volume would automatically erase this disk image, too.

On top of that, your arguments to mount are incorrect.

In this case, /dev/disk20 represents the enclosing disk image, but the actual disk data is on typically stored on a number of partitions (or slices) within the disk image itself. They're usually denoted as disk20s1, disk20s2, etc.)

For example, here's what a disk image looks like OMM:

/dev/disk4 (disk image):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        +73.4 MB    disk4
   1:                  Apple_HFS Installer               73.4 MB    disk4s1

The fact that your disk image has no slices/partitions, the fact it has no 'type' (partition or filesystem spec), tells me it isn't a valid disk image, so you may be chasing your tail.

So, again, what is it you're trying to do here?

 👍

For a native English speaker that message was painful to read.

It's also highly unlikely Apple would use the terminology "fire vault" 🙄

Camelot is right. Take a step back. Take many steps back. Don't do anything else with that Mac. Let Apple unscramble the mess on Friday.

You're welcome. Since you are not good with software I recommend stopping at this point. For whatever reason you found yourself deep in a hole. Stop digging.

The help you got from "Apple" was dubious at best. Unfortunately whoever that may have been does not report to me and there is nothing I can do about their ineptitude.

Stop before you make things worse.

Where did you get this message? It does not look like it came from Apple.

I was just commenting about it because there are many scams out there that will pretend to be Apple, remote into your machine and steal your data.