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Can't install FortiClientVPN macOS "The disk you attached was not readable by this computer"

I am trying to install FortiClientVPNOnlineInstaller_7.0.dmg on macOS Monterey 12.6.6 

I get "The disk you attached was not readable by this computer"


LE: fixed. I re-downloaded and now it magically works.

Note: The OS has been freshly updated. FortiClient has been installed before on same computer. Not sure if the installer .dmg is damaged or there are some local settings preventing the installation.

Screenshot 2023-05-24 at 15.08.36.png


Are you able to install any other applications? can you test with any other .dmg files and check, this will confirm if the issue is related to FortiClient or MAC.

- Have you found a solution? Then give your helper a "Kudos" and mark the solution.

I have installed 2 other .dmg based apps, it works, the .dmg mounts the temporary volumes.




Ensure that you are downloading the FortiClientVPNOnlineInstaller from a trusted source. Sometimes, interrupted downloads or incomplete files can lead to corruption. Try downloading the DMG file again from the official Fortinet website.
After downloading the DMG file, verify its integrity by comparing its checksum with the checksum provided by Fortinet. This step helps ensure that the file has not been tampered with during the download process.

macOS may encounter issues mounting the DMG file if it is not handled properly. Instead of double-clicking the DMG file, try using the following steps:

a. Open Finder.
b. From the menu, select "Go" and then choose "Utilities."
c. Launch the "Disk Utility" application.
d. In Disk Utility, click on "File" in the menu and select "Open Disk Image."
e. Locate and select the FortiClientVPNOnlineInstaller DMG file to open it.



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