Since Mac OS won't 'let go' an external disk containing the Photos Library (even when no Application is active...), Disk Utility can not unmount it for repair.
Any thoughts on this?
iMac, macOS High Sierra (10.13.1), disk utitlity
You can also boot into Recovery mode (⌘-R}, and use Disk Utility First Aid from there on the external drive. No process on the Mac will be associated with the Photos Library when done in this manner.
You can also boot into Recovery mode (⌘-R}, and use Disk Utility First Aid from there on the external drive. No process on the Mac will be associated with the Photos Library when done in this manner.
You might try through Terminal:
Launch/Utilities/Terminal and copy & paste this command at the prompt:
diskutil list
Press return.
If it sees the disk, note the number of the disk (far left column) you want to mount.
Then, enter this command:
unmount /dev/(number of disk)
Put in the number no parenthesis.
Press Return.
Also might try
mount force /dev/(number of disk)
How can Disk Utility repair an external disk containing the Photos Library? It can not be unmounted.
