When performing a manual apt-get upgrade command from the OMV CLI, I ran into this error when it tried to upgrade the grub-pc package.

grub-install: error: unable to identify a filesystem in hostdisk//dev/sdx; safety check can’t be performed.

where x is a device letter (e.g., sda, sdg, etc.)

The solution is pretty simple.

When presented with the Package configuration screen for grub-pc, there is the error:

GRUB failed to install to the following devices:

/dev/sdx

Do you want to continue anyway? If you do, your computer may not start up properly.

Writing GRUB to boot device failed – continue?

1. Choose the option for No.
2. Then find the correct boot device in the list and select it.  Double check that no other devices are selected.
3. Continue with the install

I was trying to perform a backup of the system C drive to another local storage D drive by using the Create a system image feature.  Each time the system image was attempted, it would result in the same error:

Windows Backup encountered an error when writing data to the backup target. (0x80780166)

Additional Information:
STATUS_WAIT_1 (0x80070001)

The system image had worked many times in the past, but it was now failing.   The only recent change to the system since then was upgrading the storage drive to a larger capacity and all the files had been migrated.

The solution was fairly simple.  I closed the Windows Backup tool and on the storage drive that had the previous backups, I found the folder titled WindowsImageBackup (located in the root of the drive).  I then renamed the folder (e.g., WindowsImageBackup-old).

When I attempted the backup again, it completed successfully.  Then I deleted the renamed folder to free up space.