How to disable gatekeeper to fix "You do not have permission to open an application"?

- Please watch the upper ☝︎ video carefully and follow the steps. (in case the video doesn't work, press on this link) 
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Sometimes while trying to open certain application on macOS, you may face messages like this:

"You do not have permission to open the application “app”. Contact your computer or network administrator for assistance.​"

This is a security problem that means that your Mac cannot identify the developer of this app and it thinks that it is unsecured to run such application. To be honest, this good but sometimes you download such app and you want to run it without restrictions (you trust the website, you downloaded this app from it.

This solution depend on disabling gatekeeper to give a permission for your application then enabling it.

What is GateKeeper?

• Gatekeeper is a security feature of the macOS operating system by Apple. It enforces code signing and verifies downloaded applications before allowing them to run.

This problem can be solved using many procedures, you can explore them here.

The above video describes the solution of this problem: 

Briefly, In this tutorial: -
- you have to disable gatekeeper using terminal command:       spctl --master-disable
- This will allow applications downloaded from anywhere to be installed.
- Followed by changing the permissions of the application using terminal command to fix the problem of your app.

(After you finish the procedure) Please do not forget to re-enable your MacBook gatekeeper using the following command: 
​ spctl --master-disable

Please do not hesitate to contact me if you faced any problem while applying the described procedure, just press the chat button. ​