Are you having trouble accessing or opening DMG files on Mac? You may have important DMG file to install application or created an image file of your macOS disk in DMG format. However, if it turns out to be inaccessible or shows error, then read this post to learn how to recover corrupt DMG files.
What is DMG file and why does it get corrupt?
DMG file format by Apple is especially formulated for Mac users. It is a disk image file having .dmg extension, which you can mount as volume on macOS and access its data. DMG files are commonly used to install software on Mac machines. Besides, users can also create disk image files of their physical macOS disks in DMG format.
Like any other file on your computer, DMG can get damaged, corrupt or lost. Many a times abrupt stopping of the file read / write process can corrupt your DMG file. Transferring the DMG file to an unsupported system, or storage drive corruption etc. can damage the file header or data of your DMG files
How to fix and recover the corrupted DMG files
There’s little you can do to repair corrupt or damaged DMG file. However, if the DMG file is not opening or its access is restricted you can try the below methods to fix and open DMG image file. Further, if you are using Time Machine, its the best way to get back the correct and working DMG file from the previous backup version.
Method 1: Fix corrupt DMG by using built-in repair utility on Mac
Your Mac has a ‘First Aid’ feature in Disk Utility. The feature helps to find and repair disk errors that may be the cause file corruption or other issues. ‘First Aid’ may fix the disk errors and making the DMG file accessible.
However, this is not a sure shot method and may result in loss of file too. Hence, as a precaution apply the repair on the copy of the DMG file and don’t forget to take the backup of your Mac before moving ahead.
Steps to repair DMG file using Disk Utility on Mac:
- On your Mac navigate to Applications > Utilities.
- From the list click to open the Disk Utility application
- Drag the corrupt .DMG file to the Disk Utility window and click on it.
- Select First Aid tab.
- Click on Repair Disk. After the repair process finishes, restart your Mac and check if the DMG file is accessible or not.
Method 2: Use Repair Disk Permissions
When you cannot access the DMG disk image file, use ‘Repair Disk Permissions’ feature in Disk Utility. May be the installer of DMG file has blocked its access. The Repair Disk Permissions repairs discrepancies in the permission settings of the application files and system files on your Mac, ensuring the correct access.
To repair disk permission of DMG file follow the below steps:
- Open Applications > Utilities> Disk Utility.
- Select the desired disk from the left pane and click on the First Aid tab.
- Click Repair Disk Permissions at the bottom.
Alternatively, you can also repair disk permissions through Terminal. Here use the following command to restore the disk image file permission: sudo diskutil repairPermissions/.
Method 3: Convert the DMG file
For many users converting the file format of the damaged DMG file worked. You can convert DMG file to IPSW, ZIP, ISO, 7z, RAR, IMG, or other. Some commonly used DMG file converters are AnyToISO, DMG2IMG, CloudConvert, etc. These tools can extract data or convert the DMG file format. Once the file converted, you can easily open its files on your Mac system.
Method 4: Restore lost DMG file from Time Machine backup
Are you using Time Machine on Mac? Check the Time Machine backup for the lost DMG file. May be the working DMG disk image file is there.
Steps to restore DMG file from Time Machine backup:
- Go to the location on your Mac from where you stored the DMG file in Finder.
- Next, click on the Time Machine icon in the menu bar and select Enter Time Machine.
- Time Machine shows the previous versions of the active folder where you have saved the DMG file. Browse through backups using the up/ down arrows. Select the DMG file you want to restore.
- Click Restore at the bottom to get back the disk image file at its original location.
Have you accidentally deleted DMG image file?
In case you have lost DMG file due to formatting, drive corruption, or deletion, don’t worry. Use a professional data recovery software for Mac — Stellar Data Recovery. The software efficiently retrieves the deleted or lost DMG file type without affecting its original quality from macOS volumes, drives, Time Machine etc. It supports the latest macOS Monterey, Catalina, High Sierra, and below versions.
To Sum Up
Your DMG image file has valuable disk data that you cannot afford to lose, be it due to corruption or deletion. If the DMG file is inaccessible or you can’t extract its data, try to fix the issue by applying Mac’s ‘Repair Disk’ or ‘Repair Disk Permissions’ feature. Converting DMG file has also proved to be helpful for many users. However, try to recover corrupt DMG files using the previous backup version in Time Machine.
Just in case DMG file is deleted from Time Machine, immediately get a professional Mac data recovery software to restore it.
The data recovery professional software is also available for Windows version.