Why the Finder Won’t Let You Extract Disc Images (and How to Fix It)
It’s frustrating when your computer doesn’t do what you ask. If you no longer need a disk image attached to your Mac and you are trying to eject it, you may encounter the error: “The disk could not be ejected because the Finder is using it.” Use for what?
While it can be annoying to ask how to extract a DMG, there is usually a simple reason why it doesn’t work.
Why can’t you extract your DMG
DMG, otherwise known as Apple Disk Image, is like a digital disk: just like you can download apps from a hard drive or USB stick, DMG allows you to install apps and can also contain other important information.
When you download a new application from the web, it will often download the DMG instead. From there, you will find the usual window instructing you to copy the application to your Applications folder, which will install the application on your computer. You then discard the DMG as it is no longer needed.
However, when you encounter this error, it can be confusing and frustrating. Who wants to look at a useless DMG on their desktop?
The most common reason you can’t extract a DMG is because you haven’t actually copied the application to your computer . If you double-click an application from DMG, you are launching that program from DMG itself. The app probably worked fine since you can run apps from the DMG, but the Finder won’t fetch the DMG as it’s currently in use. You will need to exit the application in question before you can extract the DMG.
However, if it is an application that you want to install on your computer, you must ensure that the program is copied to your Applications folder before extracting the DMG. If you extract it without doing so, you will not be able to access this application.
If you still can’t extract the DMG, try restarting your Mac. Sometimes a reboot can fix issues between your Mac and DMG, freeing you up to eject the drive.
Hard drives offer similar problems
The same problem can apply to removing hard drives. If you have a hard drive, a USB drive, or are using a physical drive, actively launching the program from the drive will prevent you from ejecting the drive.
However, sometimes it is not obvious which program can work from the disk or use its resources. In this case, it might be worth closing open applications that are not connected to the drive to check if any of them are the culprit.
Spotlight is another useful tool for finding files and apps on your Mac. However, this can also be a nuisance; this feature often works in the background, indexing your drives so you know where everything is. This background activity isn’t obvious, so if Spotlight is indexing the drive you’re trying to eject, you may not know, and it may seem like there’s no reason why macOS won’t let you eject it.
If you want Spotlight to not index your drive so you know it won’t be the cause of your eject issue, you can go to System Preferences > Spotlight > Privacy . Select (+) , then select the mapped drive.