Written by
Yvonne FengSummary: This post explains why you can't open a DMG file on Mac. Besides, you can learn how to fix it if you are unable to open a DMG file. Download iBoysoft DiskGeeker for Mac to avoid the problem caused by insufficient disk space.
DMG files are a commonly used format in macOS, primarily for software installation, data storage, and backups. Normally, macOS natively supports DMG files, allowing you to simply double-click to mount them and access a virtual disk in Finder.
After the latest update of my Mac to Sequoia, I can't open any dmg files and am not able to install anything. Tried to attach it through erminal, doesn't work either. - Apple Community
I was migrating some data I stored in a password-protected dmg file from an old MacBook to a new one. Now I can't open the dmg file by just double-clicking it! - Apple Community
However, some users have reported issues like they can't open DMG files on Mac after upgrading to macOS Sequoia. If you're experiencing a similar problem, follow us to resolve it.
Can't Open the DMG File on Mac, how do I fix it?
For some reason, you may be unable to open a DMG file on your Mac. You can try the following methods to resolve the issue.
- Check the DMG file
- Free Up Storage Space
- Manually Mount the DMG File via the Terminal
- Open DMG File Using Disk Utility
- Reset the NVRAM & SMC
Method1. Check the DMG file
If the DMG file is incomplete, corrupted, or improperly downloaded, macOS may fail to mount it. This can happen if the download was interrupted or if the file was damaged during transfer.
So, you should open Terminal to check if the file is corrupted. Type the following command and press Enter. If you see an error, the file is likely corrupted. At this time, you need to go to the official website and download the DMG file again.
hdiutil verify ~/Downloads/yourfile.dmg
At the same time, you can also try opening it on Another Mac to avoid the issue caused by your Mac.
Method2. Free Up Storage Space
Enough storage space is necessary for you to open a DMG file on Mac. When a DMG file is mounted, macOS generates cache and temporary files. If there isn't enough space, the system may fail to create these essential files, leading to a mounting error.
You can check your available space by clicking the Apple menu > About This Mac > Storage. If there is not enough disk space for opening a DMG file, try deleting some unnecessary files manually. Alternatively, for a quicker and more efficient cleanup, you can use a disk management tool like iBoysoft DiskGeeker for Mac.
It is a professional disk management tool that quickly identifies large files on your Mac, making it easy for you to delete unwanted ones. It also scans for cache files, temporary files, system logs, and other junk data. With just a click on Clean, you can quickly remove these unnecessary files and free up storage space.
So, why not download it and have a try?
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Method3. Manually Mount the DMG File via the Terminal
Sometimes, macOS Finder fails to mount a DMG file automatically. Using the Terminal can force it to mount.
- Open Terminal (Applications > Utilities > Terminal).
- Type the following command and press Enter:hdiutil attach ~/Downloads/yourfile.dmg
- If successful, you should see an output indicating that the DMG has been mounted.
Method4. Open DMG File Using Disk Utility
If the DMG file isn't mounting normally, try to manually mount it through Disk Utility.
- Open Disk Utility (Applications > Utilities > Disk Utility).
- Click File > Open Disk Image, then select your DMG file.
If you see errors, click First Aid and run a repair.
Method5. Reset the NVRAM & SMC
If you can't open a DMG file on your Mac, it could be due to system settings, hardware management, or power control issues. Resetting the NVRAM (Non-Volatile Random-Access Memory) and SMC (System Management Controller) can help resolve these problems.
Reset NVRAM (Intel Macs only)
- Shut down your Mac.
- Turn it on and immediately hold Option + Command + P + R for 20 seconds.
- Release the keys and let your Mac restart.
For Apple Silicon Macs, just restart—NVRAM resets automatically.
Reset SMC (Intel Macs only)
- Shut down your Mac.
- For MacBooks: Hold Shift + Control + Option and press the Power button for 10 seconds, then release.
- For desktops: Unplug for 15 seconds, then reconnect and turn on.
Apple Silicon Macs don't need an SMC reset—just restart.
Finally, try opening the DMG file again after resetting.
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Why can't open the DMG File on Mac?
If you can't open a DMG file on your Mac, there could be various reasons preventing it from mounting or installing properly such as file corruption, system compatibility issues, permission settings, security restrictions, etc.
- Corrupted DMG file: If there was an error during the download process, the DMG file might be corrupted, preventing it from mounting properly.
- macOS version incompatibility: Some DMG files are designed for newer or older versions of macOS, which can cause compatibility issues.
- Permission issues: If the DMG file lacks the necessary permissions, you may need to manually adjust them or open the file with administrator privileges.
- Security restrictions: macOS Gatekeeper may block DMG files from unverified developers, preventing them from opening.
- Insufficient disk space: DMG files often require temporary extraction to disk, and a lack of available space can cause mounting failures.
- Invalid disk image: Some DMG files are not standard disk images but rather fake or encrypted files, making them unrecognizable.
- System errors: macOS may fail to mount the DMG due to cache issues or other system-related problems.
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