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I get an error "App can't be opened because it is from an unidentified developer” in Mac OS X Mountain Lion

Last Updated: Jan 19, 2015 12:25PM CET
This article talks about a warning message in different versions of Mac OS X that prevents you from installing Liquid Notes.

Quick answer: Right-click (or control-click) on Liquid Notes in the installation package and select "Open" from the drop-down menu. Then, in the dialog box click on the button "Open" to start the installation.

Update (Nov 2014): A number of customers have reported running into this problem after having upgraded to Mac OS X 10.10 (Yosemite). We can confirm that our applications are correctly signed, yet it remains unclear why reading back the certificate fails with some people on OS X 10.10.


Fix the app can’t be opened error

Since Mac OS X 10.8 (also called: "Mountain Lion") Apple has included a security feature called GateKeeper that prevents applications from unidentified developers or sources from being launched. This results in the error message shown hereafter being displayed when trying to launch an app that didn't come through a verified source or from the Mac App Store:

Error message "App can't be opened because it is from an unidentified developer."

This doesn't mean you can't run those apps from an unverified source on your Mac. You'll have to temporarily disable the safety net of GateKeeper, or turn off app limitations in its entirety.

Disable "App can't be opened .." message temporarily

Follow these steps to disable the warning message temporarily:
  1. Right-click (or control-click) Liquid Notes and select "Open".
  2. Click the "Open" button at the next dialog.

    Click the "Open" button to enable Liquid Notes to always run on your Mac.

This enables Liquid Notes to run always on your Mac. 

Disable "App can't be opened .." for all apps permanently

If you get tired of right-clicking apps to open them, you may as well turn off the newly added security feature of Mac OS X Mountain Lion: 
  1. Launch 'System Preferences' from the Apple Menu (to locate it find the Apple logo, and click on it)
  2. Choose 'Security & Privacy' and then click on tab 'General'. If the lock icon (in the bottom left corner) is set to 'locked', click on it to unlock making changes to these settings.
  3. Go to 'Allow applications downloaded from:' and select 'Anywhere'.
  4. Acknowledge the security warning, and close the settings window

App verification has been turned off completely! You can now launch any application from any developer.

Disclaimer: This article originally appeared at OS X Daily, and was reproduced and adapted for use here. All rights remain with OS X Daily.

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