What To Do When Your .DMG File Is Not Opening on Mac

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DMG files simplify app installation on macOS by allowing you to double-click and drag the app to your Applications folder, then unmount the installer. They undergo a checksum process to ensure their integrity. However, some users may experience issues opening DMG files on their Mac, which this guide aims to address.

Fixing Issues with Unopenable .DMG Files on Mac

Opening a DMG file on a Mac should be simple, but some users are unable to do so. Despite downloading and unzipping the file without issues, nothing happens when trying to open it. Some users receive a ‘resource temporarily unavailable’ error, while others see no activity. The error message ‘no default application specified to open the document’ can also appear. This problem has frustrated affected Mac users. Redownloading the file on another Mac resolved the issue for some, suggesting a problem with the device itself. Various factors could contribute to the inability to open DMG files on Macs.

Why Your .DMG File Is Not Opening on Mac

Some Mac users have trouble opening DMG files, whether they are using the newest Catalina version or an older macOS. There are a few reasons why this happens:

  • Catalina doesn’t support 32-bit apps, so make sure you download the 64-bit version of the app you want to use.
  • A weak or unstable internet connection could cause download errors or incomplete downloads.
  • Downloading a DMG file from an untrustworthy source could lead to malware infection or fake files.
  • DMG files can become corrupted during the download process or due to malware infection.

To fix these issues, try these tips:

Pro Tip: Scan your Mac for performance issues, junk files, harmful apps, and security threats
that can cause system issues or slow performance.

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  • Download the file again using a different internet connection, preferably a wired one.
  • Scan the file for malware before opening it, especially if downloaded from an untrustworthy source.
  • Download the app from a trusted source, such as the Mac App Store or the developer’s website.
  • Make sure to download the 64-bit version of the app if you’re running macOS Catalina.

How to Open .DMG File on Mac

If you’re struggling to open a DMG file on your Mac, there are several methods you can try.

  • Method 1 involves using DiskImageMounter, while
  • Method 2 involves using Terminal to mount the file. If neither of those work,
  • Method 3 suggests using a third-party tool.

To use Method 1, right-click on the file and choose Open With, then select DiskImageMounter. If you don’t see the Disk Image, navigate to /System/Library/CoreServices/DiskImageMounter.app.
For Method 2, drag the file to the Desktop, open Terminal, and type ‘cd ~/Desktop’ and ‘hdiutil attach filename.dmg’ (replace ‘filename’ with the actual name of the file).

If these methods don’t work, you can try a third-party utility:


Installing applications on macOS is relatively easy thanks to the DMG file, which simplifies the process compared to Windows. However, it’s common to experience errors when opening DMG files, especially if the file is corrupted or hasn’t fully downloaded. To resolve this issue, there are three methods to try. The first involves using DiskImageMounter, while the second uses Terminal to mount the file. If neither of these methods works, a third-party tool may be necessary.

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2 years ago

That terminal fix for installing a .dmg worked. I couldn’t believe it. Thanks so much!

2 years ago

Same here — I am so grateful to have found this page. FYI, in case it drives traffic to your page and helps out other people in my situation, I was trying to mount Quickbooks for Mac 2019 on a computer running Big Sur.

Ujjwal Kumar
2 years ago

Just restart your system once before trying any other stunt. That worked for me after wasting at least an hour 🙂

1 year ago

Thanks, it worked!

Xavier Wallace
3 months ago

the terminal cmd works, but how could I do this for a dmg inside of a dmg, It doesn’t seem to work

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