Generally, when you got the warning message "This disk wasn't ejected because one or more programs may be using it", you can't eject the external hard drive on Mac safely. Just as the error itself states, it may be because the external hard drive is currently in use or the drive is engaged by a processing program.
You've learned that forcing quit all running apps or relaunching the Finder may help fix this issue. Shutting down your Mac computer is also a fix. If you're not satisfied with the abovementioned 3 fixes. Here we'll offer you another 2 ways to fix "This disk wasn't ejected because one or more programs may be using it" on Mac.
Method 1: Eject the disk by Terminal
Step 1: Open Mac Terminal from Mac Dock or Launchpad, running the following command to force eject the disk from your Mac.
Step 2: Type in the following two commands.
diskutil list external diskutil eject disk (number)
Remember to replace the disk number with the right disk number of your external hard drive in the command list.
Now, your external hard drive should be ejected successfully from your Mac.
Method 2: Eject the disk with an automatic ejection tool
If you don't want to use Terminal, you can use iBoysoft NTFS for Mac instead. Although It is mainly designed for mounting Windows NTFS file system drives on Mac, it can also be used to fix the 'external drive won't eject on Mac' issue.
- Free download and launch iBoysoft NTFS for Mac.
- Wait for the app to detect your disk with the issue.
- Click the iBoysoft NTFS for Mac icon in the menu bar, select the drive from the drop-down list, and choose Eject.