This guide will walk you through step by step on how to fix “App Can’t Be Opened Because It Was Not Downloaded From The Mac App Store” error in Mountain Lion. Apple made the default setting to only allow Apps downloaded from the App Store to run. This causes issues when using Hackintosh applications because the majority of them are not available through the App Store.

Index:

Accreditation
Section 1: Enable Third Party Applications

Guide:

Accreditation:

Andrew Kern – Publisher
Nick Smith – Editor

Section 1: Enable Third Party Applications

1. The following is a example of an Error Message when trying to run a Application not Downloaded from the Apple Store:

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2. Go to System Preferences:

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3. Then under the Personal tab go to Security & Privacy:

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4. Go to the General tab and unlock the menu:

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5. Now under the Allow applications downloaded from section select Anywhere:

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6. Now you should be able to successfully run the app you were trying to run.