Can't eject disk image from Finder in Mountain Lion

How about when you drag the image or drive to the trash?

It won't drag to the trash? Describe exactly what happens when you do that.

If you select the object and do a command-e will it eject?

Have you emptied the trash? I have found that if there is anything in the trash that came from the disc image, the disc image will sometimes fail to eject.

Also, even though you have nothing open ("in use") in the disc image, are there any apps that are open that were used with something in the disc image? Make sure that all apps are closed.

Boot into the ML recovery Disk and run Repair Disk from Disk Utility.

I am having similar issues with my user account. It also is the same in Yosemite.

Disc images, external hard drives etc dragged to trash (get eject icon) are simply ignored.

Pressing Eject button in side bar of Finder are ignored.

It seems to be a permission/account issue as:

- using computer under a different account doesnt have this problem

- transferring account over to another mac continues the problem on the new computer.

Log file seems not to have any errors.

I have this same problem as well.

Started when I upgraded my 2010 MacBook Pro from Snow Leopard to Mavericks in 2014 and it carried across to my new 2014 MacBook Pro Retina when I used Migration Assistant.

Extremely annoying. I've been using Disk Utility to unmount hard drives and disk images for nearly 2 years now. Thinking the only way around it is to freshly install OS X again and all the apps.

Frankly, getting quite sick of perfectly simple feature of Mac OS starting to fail and Apple not picking it up during testing.

I had similar issue since a long time too.

A simple fix: use Onyx (free and solid utility software), and go to Parameters > Finder > Show Eject. And you should be good!

It works.

Was having this problem. This fix worked on High Sierra

Which fix are you talking about? Using Onyx, you mean?