could not unmount disk when formatting usb mac

Lsof | grep /Volumes/'Install macOS High Sierra' Unmount of disk1 failed: at least one volume could not be unmounted Sudo dd if=/dev/zero of=/dev/disk1 bs=10000000ĭisk1 was already unmounted or it has a partitioning scheme so use 'diskutil unmountDisk' instead Started erase on disk1 Unmounting disk Error: -69888: Couldn't unmount disk Sudo diskutil eraseDisk JHFS+ Lexar disk1 Using the Terminal app with the following commands:

Using Disk Utility app, but it does not see the USB or just keeps spinning. Would you have any suggestions or ideas? Also, I don't understand what PID 0 is doing to prevent me from erasing the USB. Now that I’m done with it, I cannot erase it. Let me know if this was helpful in the comments.I created a bootable USB with High Sierra on it.

Then this: diskutil erasedisk is the ID of your disk.

Type this very carefully (sudo might not be necessary): sudo diskutil unmountDisk force /dev/disk2.

(note: be EXTREMELY careful, ask you could wipe your computer if you do this wrong) Thankfully I ended up fixing it quickly (with a little googleing). I was getting things like: ”could not modify partition map” and “couldn’t unmount disk.” Other things could be things like “couldn’t open device.” Erasing an External USB or Hard Drive that keeps failing in Disk Utility You get this error, and the details vary depending on the format type you try That might be because the disk is a Windows/Linux bootable formatted as FAT-32, which OSX cannot read.Īnd then when you try to erase in disk utility, the USB is greyed out and First Aid doesn’t work, you can’t repair it, and you can’t mount or unmount it.

Are you trying to erase a USB drive on your mac but getting this error as soon as you insert it?

Could not unmount disk when formatting usb mac