Firefox can't be opened after you install it on a Mac - How to fix

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  • Revision id: 76765
  • Created:
  • Creator: Joni
  • Comment: first draft
  • Reviewed: Yes
  • Reviewed:
  • Reviewed by: jsavage
  • Is approved? Yes
  • Is current revision? No
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This issues applies to Mac devices only.

Apple has made a security change to Mac OSX 10.9.5 which causes the error message Firefox.app cannot be opened because the identity of the developer cannot be confirmed to appear when you try to install Firefox on your Mac.

This issue has been resolved on newer versions of Firefox, but if you see this message while trying to install a version prior to Firefox 32, here are some steps you can take:

Option 1 - Recommended

  1. Hold down the Control key while clicking on the Firefox file.
  2. Click Open on the dialog window.

Option 2 - Open Firefox through the System Preferences

  1. Click on the Apple icon at the top left corner of your screen and open System Preferences.
  2. Click on Security & Privacy, then the General tab.
  3. You'll see a message stating that the Firefox.app was blocked. Click on the Open Anyway:
    blocked firefox mac