Opening .pdf files with Preview - Gatekeeper says: xxx can't be opened because it is from an unidentified developer

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Level 1

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Opening .pdf files with Preview - Gatekeeper says: xxx can't be opened because it is from an unidentified developer

As above, Gatekeeper displays the message: ['FileName'.pdf] can't be opened because it is from an unidentified developer.

This only started happening after I changed the default programme to open .pdf files from Adobe Reader to Preview (serious speed issues with Adobe) - using the 'Open with' > 'Always Open With' option.

This is clearly a Gatekeeper action as appropriate for the "Mac App Store and identified developers" Gatekeeper option setting in System Preferences - EXCEPT this normally applies to apps and not individual files!

I could do all the usual right-click Open options to override it but I found it only applied to that individual .pdf file and when opening another I would get the same dialogue popup. This Gatekeeper behaviour only applies to .pdf file recently downloaded from the Internet it seems and pre-existing .pdf files open normally with Preview no problem.

I have temporarily overcome this by downgrading the Gatekeeper security settings to 'Anywhere' but this is not a proper fix - does anyone have any ideas about this?

Thanks 🙂

MacBook Pro, OS X El Capitan (10.11.2), MacBook Pro (15-inch, Late 2011)

Posted on Jan 4, 2016 3:18 AM

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Answer 1

Linc Davis

Level 10

209,739 points

Jan 4, 2016 8:06 AM in response to MrsJames

Please restart the computer in safe mode. Certain caches maintained by the system will be rebuilt.

Safe mode is much slower to start up than normal. The next normal startup may also be somewhat slow.

When the login screen appears, restart as usual (not in safe mode) and test. There's no need to log in while in safe mode.

Note: If FileVault is enabled in OS X 10.9 or earlier, or if a firmware password is set, or if the startup volume is a software RAID, you can’t start in safe mode. In that case, ask for instructions.

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Answer 2

MrsJames Author

Level 1

0 points

Jan 4, 2016 9:43 AM in response to Linc Davis

Before I got your reply I applied the latest 10.11.2 combo updater but that didn't seem to fix it even though it went through the various system checks and restarts etc.

Then I saw your message and so I restarted in Safe Mode, restarted in normal mode - everything very slow to start but got there in the end.

Have reset the Gatekeeper settings back to "Mac App Store and identified developers" and tested I still getting the following symptoms:

When I try to open a newly downloaded .pdf Preview starts up but I get this:

Other .pdfs that I have previously permitted as safe will open OK with Preview
Some of the .PDF files on my Desktop show Adobe PDF icons and some sow the Preview PDF preview of the file for the icon - like the above file for example but this does not appear to affect behaviour, it just seems to be another anomaly
When I download a .pdf I get this which oddly seems to show Adobe Reader as the default:

When I double-click on the downloaded file in the downloads folder, which has an Adobe icon, it opens with Adobe Reader
When I make a copy of it and paste it on the desktop it saves with a Preview icon but still opens with Adobe Reader
Then I noticed that the 'Open with' option in the properties of the two different files were different as below:

After doing the 'Change All' thing the system seems to be returned to normal functioning as far as opening .PDF files with Preview goes...

🙂

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