The file that downloaded is now on my desktop as X17-45975.dmg When I go to open the file, I get a pop-up window that says The following disk image couldnt be opened; Reason is listed as 'not recognized' Is there a solution to fixing this vs having the file download for another 4 hours??? Image Not Recognized Dmg Files Mac Free Aside from the Finder application, you can open DMG files through Apple Disk Utility, Roxio Toast, and Dare to be Creative iArchiver for Mac platform. On the other hand, additional applications such Acute Systems TransMac, DMG2IMG, and DMG2ISO can be installed on Windows to fully support the files.

I ran into an interesting macOS error while working with a customer. I didn't find a lot of good search results addressing the issue, so I decided to write up a post about it myself.

The error was as the screenshot above shows; trying to open a dmg (disk image), macOS showed the error 'no mountable file systems'. If you see the 'no mountable file systems error' while opening a dmg, here's what you should try:

1. In most cases, the downloaded dmg file is actually corrupt or had an error downloading. If possible, try downloading the dmg again, turning off any download assistant plug-ins you may have. You can try downloading the file in a different browser as well. Or if you don't need to be logged in to the site to download the file and you want to be fancy, you can try curl -O url in Terminal to download the file. (There's an example of that in my screenshot below.)

2. Reboot your Mac if you haven't already tried that. Apparently there is an issue sometimes after opening too many dmg files, that is fixed with a reboot.

3. Try mounting the DMG on the command line in Terminal. We will at least get some sort of useful error message to go on if it still fails:

   • Open Terminal: In Spotlight, the search magnifying glass at the upper right corner of your screen, search for Terminal, and press enter to open the Terminal app.

   • Type hdiutil attach -verbose into the terminal. Add a space at the end, but don't press enter yet.

   • Drag the dmg file from your Finder window onto the Terminal window and let go. This will fill in the location of the dmg file into your Terminal window.

   • Press enter.

4. macOS Sierra (10.12) and earlier is not able to mount the new Apple File System (APFS). So if you're on macOS Sierra (10.12) or earlier and you ran hdiutil and see references to Apple_APFS or error 112, the issue is likely legitimate incompatibility, and this disk image won't open on this Mac without an update to the operating system.

   Here's an example of the end of hdiutil attach -verbose output that shows an APFS error due to an older version of macOS:

5. Think about if you have any kind of security policies on this machine to prevent writing to external drives (thumb drives, optical drives, etc). I haven't seen this one in action, but I read about this being a possibility while researching the issue.

6. Another suggestion added by a reader (thank you, Markus!) is that filesystem errors on your main Mac drive could be the cause of the disk image mounting errors. Here are instructions from Apple for scanning and repairing errors using Disk Utility. Note that in order to scan and repair errors on your main Macintosh HD drive, you'll need to reboot your Mac into recovery mode. You'll want to choose Disk Utility in the utilities listed in the recovery mode menu.

7. A new discovery from a reader (thank you, Colby!) is that APFS DMGs won't mount if you're booted in macOS booted in Safe Mode. (Who knew!?!) If you're not sure if you're in safe mode, select the Apple menu  > About This Mac > System Report button, then select the 'Software' heading from the left column. To exit safe mode, restart your Mac, without holding Shift during startup. Or, if you previously set your Mac to always boot into safe mode using nvram, turn off safe mode and have your Mac boot normally on the terminal:

   • Open Terminal: In Spotlight, the search magnifying glass at the upper right corner of your screen, search for Terminal, and press enter to open the Terminal app.

   • Type/paste sudo nvram boot-args=' and press enter.

   • Restart your Mac.

8. Another new discovery (thank you, Iris!) is that if you have APFS by Paragon software installed on a Mac that can read APFS itself, it can interfere with opening the DMG. So if you used APFS by Paragon and then updated your Mac, you may need to uninstall it.

One footnote for people having issues opening ISO files. Another new discovery is that 'hybrid' ISO files (think Linux installers) don't open correctly automatically and need to be manually attached and mounted (this is NOT advice for normal .dmg files.) Credit to the this superuser.com discussion and this Apple forum discussion for solutions.

When you download an app or a piece of software on your Mac, the file is usually downloaded as a DMG file. DMG files serve as containers for apps in macOS. You just need to double-click the downloaded DMG file, drag the app to the Applications folder, then unmount the installer. This way, the installation process has been simplified and users don’t have to suffer the hassle of installation wizards that are plaguing Windows users.

Although the installation process sounds simple, it is much more complicated than that. The contents of the DMG goes through a checksum process to verify that the file is 100% intact and that it hasn’t been tampered with. Once the file has been verified, it is then decompressed. DMG files are designed for macOS and you can’t run them on Windows devices.

DMG files make app installations on macOS a lot quicker and easier. However, there have been several reports from users about the .dmg file not opening on Mac. There are different versions to this error, but the end scenario is the same: for some reason, users are unable to open the .dmg file on Mac. This guide will discuss why some users have trouble opening a DMG file and how to resolve this issue.

Unable to Open .DMG File on Mac

Installing a DMG file on Mac should be as easy as double-clicking the file and dragging the app to the Applications folder. However, the process is not as smooth for some Mac users because they are not able to open the DMG file to start with. According to user reports, the download process was completed and there were no issues with unzipping. But when it comes to opening the unzipped files, nothing happens. Some users who encounter this issue get the resource temporarily unavailable error while others noted no activity happening no matter how many times the file is clicked.

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Others encounter this error message when opening the DMG file:

There is no default application specified to open the document.

When the user tries to open it, either the options are grayed out or nothing happens when any of the options are clicked. This error has caused the affected Mac users to be frustrated. The users who encountered this error tried to redownload the file using a different Mac and the DMG file seems to be working fine, which means that the problem lies with the device itself. But what causes DMG files to not open on Mac?

Why Your .DMG File Is Not Opening on Mac

Some users noted that they cannot open the .dmg file on Mac after updating to Catalina, but there are also those who encountered this error when running an older version of macOS. This means that the problem is not unique to Catalina but it is something that affects the entire macOS system.

Here are some of the possible reasons why some users are having trouble opening DMG files:

• If your Mac is running Catalina, check the version of the app you are trying to open. Catalina no longer supports 32-bit apps. So if you’re trying to download and install a 32-bit app, then you might not be able to install it on Catalina.
• If you have poor or unstable internet connection, it is possible that the file was not downloaded completely, resulting in errors when accessing the file.
• If you downloaded the file from an untrustworthy source, it might be a fake DMG file or it could be loaded with malware.
• It is also likely that the DMG file you downloaded is corrupted. An interrupted download process and malware infection are the two leading causes of file corruption.

Hence, before you start the troubleshooting process, here are some things you need to consider:

• Download the file once again using a different internet connection. Try using a wired connection if possible.
• Scan the file for malware infection, especially if the file was downloaded from an untrustworthy source.
• Download the file from another source. If the app is not available on the Mac App Store, visit the developer’s website and download the installer from there instead.
• If you’re running macOS Catalina, make sure that you are downloading the 64-bit version of the app.

Image Not Recognized Dmg

How to Open .DMG File on Mac

Image Not Recognized Dmg Files Free

If you’re having trouble opening the DMG file on Mac, here are some of the things you can do:

Method #1. Use DiskImageMounter.

1. After downloading the DMG file, right-click or Command + click on the file.
2. Choose Open With from the menu, then select DiskImageMounter.
3. Depending on the size of your file, you should see the mounted Disk Image appear on your Desktop.
4. If you don’t see the Disk Image, choose Other from the right-click menu.
5. Navigate to /System/Library/CoreServices/DiskImageMounter.app
6. The DMG file should now be mounted.

Method #2. Mount the .DMG File via Terminal

If the right-click menu is grayed out or nothing happens when you click any of the Open With options, you can try mounting the file using Terminal instead. Drag the file to the Desktop and follow the steps below:

1. Open the Terminal app by going to Finder > Applications > Utilities.
2. In the Terminal window, type in the following command and press Enter: cd ~/Desktop
3. Next, type in this command, then press Enter: hdiutil attach filename.dmg
4. Replace filename.dmg with the actual .dmg file name.
5. After executing the two command lines, your .dmg file will now be mounted on your Mac.

Method #3: Use a Third-Party Tool.

Image Not Recognized Dmg Files List

If you cannot open the DMG file using the two methods above, you can try using a third-party utility instead. Here are some of the apps you can try:

Image Not Recognized Dmg Files Download

Summary

Installing applications on macOS is a lot simpler compared to installing programs on Windows, thanks to the DMG file. However, it is normal to run into errors when opening a DMG file, especially if the file has been corrupted or has not been completely downloaded on your device. If this is the case, you can try any of the three methods listed above to open the problematic DMG file.