MacOS – Partition issues after deleting Core Storage Logical Volume Group. Everything prompts an unmount error

disk-utilityhard drivemacospartition

I followed the instructions in Restore Macintosh HD to its original partition configuration to delete the Core Storage Logical Volume Group via terminal while pressing Cmd+R during startup.
These are the functions I used in terminal:

diskutil cs list
diskutil cs delete <Logical Volume Group UUID>

Now I cannot resize the partition via Disk Utility. The post mentioned that a red error message would appear when selecting the drive, but that didn't happen. I'm stuck!

When I try entering "diskutil cs list" in Terminal it returns:

No CoreStorage logical volume groups found.

These are screenshots from the errors in Disk Utility:

Disk Utility

After resizing the top partition by dragging down and clicking "Apply", an error message prompts: "Couldn't unmount disk". Also happens after I repair the disk.

Couldn't unmount disk.

When restarting the computer, a grey screen with error icon appears.

Error icon on boot

Best Answer

I recommend:

  1. Restart to Internet Recovery Mode by pressing alt cmd R at startup.
    The prerequisites are the latest firmware update installed, either ethernet or WLAN (WPA/WPA2) and a router with DHCP activated.
    On a 50 Mbps-line it takes about 4 min (presenting a small animated globe) to boot into the recovery netboot image which is loaded from an apple server.
  2. In the opening window choose 'Disk Utility' and erase/format/partition the internal drive. Choose '1 Partition' 'Mac OS Extended (Journaled)' and GUID partition table (available with the 'Option' button). Quit 'Disk Utility'.
  3. Plug in your Time Machine backup drive.
  4. Start 'Restore From Time Machine Backup' and recover your old system

Instead of recovering your old system after step 2 you may install a new system by clicking on 'Reinstall OS X' and continue later with the steps 3. & 4. and recover your personal data only:

reinstall OS X

Related Question