App Launching errors

Mac users normally face the following 4 potential errors during launching App (DMG file) under Mac OS X:

CASE 1: Common errors:

  • “The App” can’t be opened.
  • And more….(you may face the differences)

CASE 2: Common errors:

  • “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.
  • And More…(you may face the differences)

Whatever error you have faced, just take the following solutions in both CASE 1 and CASE 2 to get rid of trouble?


The error of “The app can’t be opened” appears when executing the application is a fail.

The app can't be opened

To fix this, you just need to chmod it to make it executable by running the following Command line through Terminal (Found in /Applications/Utilities/):

chmod +x*

TheAppName is the App name. To avoid complicated things, you should rename the Original App name and make it without “Space” and special characters. For example, I faced the error: The application “Call of Duty 4: Modern Warfare” can’t be opened like the above screenshot. How did I fix? First, I changed the Name from “Call of Duty 4: Modern Warfare” to “Call-of-Duty-4-Modern-Warfare“, and then I entered the following command line through Terminal:

chmod +x /Applications/*
chmod +x*

And then the problem is gone and you can rename the app Back to the original name or whatever now!


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.