I was trying to run a Java applet (downloaded) through the jnlp file which came with it. And I see this error always.

enter image description here

I looked into the code signing certificate, and its signed from a trusted CA, and the expiry is not until 2020.

So, I narrowed down the issue to the problem mentioned in the following link: Fix the “App can’t be opened because it is from an unidentified developer” Error in Mac OS X which says that OS X has prevented any app from an external developer to not run. This change was made to Gatekeeper.

But, I was not able to find an official release doc which talks about this change.

Another place I heard that Apple has stopped the usage of Java applet all together. Did not find any official doc about that also.

Can anyone point me to a link to an official doc about these updates?

1 Answer 1


To open the app right-click it and click 'open'. This will open the app with Apple's Gatekeeper (System Preferences > Security & Privacy > General) still activated.

You can see more about this on Apple.com (WWDC video) and on Apple's Developer pages.

Other URLs:

Mac App Store and identified developers (default in OS X Mountain Lion) – Only allow apps that came from the Mac App Store and developers using Gatekeeper can open.

Gatekeeper gives you two security options. The default option allows you to download apps from the Mac App Store, as well as those from other sources that are signed with an Apple ID.

Users can set Gatekeeper to download and install:


Apps from the Mac App Store and apps signed with a Developer ID (this is the default setting) With the default setting, if an app is unsigned, Gatekeeper blocks the app from installing and warns users that the app did not come from an identified developer. Users can choose to override Gatekeeper or change the settings.

  • Thanks. I did read about this in the article whose link I have shared in the answer. I wanted to know about any official doc which points to these updates.
    – Haris
    Sep 28, 2017 at 11:30
  • I've added two URLs. The latter is the official documentation.
    – oa-
    Sep 28, 2017 at 11:37
  • Thanks. I haven't seen the video, but the official document link talks about the changes to Gatekeeper which needs app to be signed with version of signatures (one in the new OS version also). I was not able to find any statement saying that no outside app will work.
    – Haris
    Sep 28, 2017 at 11:43
  • So you are looking for an official documentation that says "by default macOS users can only open apps from the Mac App Store or by signed developers"?
    – oa-
    Sep 28, 2017 at 11:47
  • Yes.. Things mentioned in official docs are vague. Also, when they talk about "signed developers", they mean developers with the apple dev ID..
    – Haris
    Sep 28, 2017 at 11:53

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