disk image resize

Does the image have enough free space to be made smaller?

If you still cannot resize the image, then create a new one of the size you want and transfer the contents of the original image to the new image. After making sure the new image can be unlocked, mounted, accessed, and you confirm the files can be read, then and only then delete the original image file. Make sure you have a good backup first, just to be safe.

CMEH87 wrote:

I have a disk image (DMG) that I originally allocated 100 GB, but I am not trying to free up space and want to resize the DMG to 50 GB. When I go into Disk Utility and enter the password for the DMG, I get the following errors: "Image resize failed. The selected disk image can not be resized" (when unmounted) and "The selected disk image can not be resized. Resource temporarily unavailable" (when mounted). Any suggestions on how to scale back this DMG to open up more space on my Mac would be appreciated!

Resize a disk image using Disk Utility on Mac - Apple Support

Copy the disk image off to a different drive and once you are satisfied that you have an Additional workable BACKUP of the file, delete the original to free its entire space from your boot drive.