App Launching errors

Mac users normally face the following 3 potential errors during launching App (DMG file) under Mac OS X:

  • “The App” can’t be opened because it is from an unidentified developer.
  • “The App” is damaged and can’t be opened. You should move it to the Trash.
  • “The App” is damaged and can’t be opened. You should eject the disk image.

How to fix and get rid of trouble?

This happens when we attempt to open a DMG file that is not downloaded from App Store.

Just take the following Solutions. If the Solution 1 does not work on MacOS Sierra or High Sierra, take the Solution 2.


From Mac OS X desktop, Apple  menu > System Preferences > Security & Privacy > Select “General” tab.

  • Under  “Allow applications downloaded from”, Check on “Anywhere” if you are using Mac OS X El Capitan, Yosemite, Mavericks, ….. and “App store and identified developers” if using MacOS Sierra or High Sierra. If the problems remain the same, take the Solution 2.

Solution 2:  

Normally we take this solution when “Anywhere” is not visible.

You need to Disable Gatekeeper completely through Terminal. How to do?

  • From Mac OS X desktop, Click on Launchpad at the Dock > Others > Launch Terminal app (you can also find Terminal in/Applications/Utilities/).

  • Enter the following command into the Terminal window:

sudo spctl --master-disable

  • Hit return and enter the admin password as usually required by sudo, and Gatekeeper will instantly be disabled.
Disable Gatekeeper through Terminal
  • If you go to System Preferences > Security & Privacy > Select “General” tab, you will see the difference. You know can run the app without any problems.
Allow Applications downloaded from Anywhere is visible in MacOS Sierra after Disabling Gatekeeper

Enjoy and share if the topic may be helpful on the others.