File is damaged and cannot be opened

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Level 1

10 points

File is damaged and cannot be opened

I am running macOs 10.12.6. Suddenly Firefox 65.0 broke down and I was told to delete it and re-install it. I downloaded it from Safari but then I couldn't open the install file. I got the error message: ”The file is damaged and cannot be opened.” I keep getting the same error message when I try to install other apps, including from appStore. I re-installed Os 10.12.6 but the issue remains. I made a control download from apple.com, a pdf called ”Welcome_to_Snow_Leopard.pdf”, but it is ”damaged too”. When I open the same pdf on another Macintosh it opens with no problem.

Mac Pro, 10.12

Posted on Feb 12, 2019 10:23 AM

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Answer 1

Eric Root

Level 10

684,027 points

Feb 12, 2019 10:58 AM in response to torbjorn160

Try setting up another admin user account to see if the same problem continues. Please post back on whether or not this worked. Also try the Safe Mode. Please post back on whether or not this worked.

Isolating an issue by using another user account

Safe Mode - About

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Answer 2

Eric Root

Level 10

684,027 points

Feb 15, 2019 11:48 AM in response to torbjorn160

Might be a corrupt .plist.

Do a backup, preferably 2 backups on 2 separate drives.

Quit System Preferences.

Go to Finder and select your user/home folder. With that Finder window as the front window, either select Finder/View/Show View options or go command - J. When the View options opens, check ’Show Library Folder’. That should make your user library folder visible in your user/home folder. Select Library. Then go to Preferences/com.apple.systempreferences.plist. Move the .plist to your desktop.

Restart the computer, open the application, and test. If it works okay, delete the plist from the desktop.

If the application is the same, return the .plist to where you got it from, overwriting the newer one.

Thanks to leonie for some information contained in this.

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Answer 3

torbjorn160 Author

Level 1

10 points

Feb 13, 2019 2:51 PM in response to Eric Root

I found a web page that describes exactly my issue, only that my issue also includes downloaded files like PDF etc.

I have checked in the system preferences, and my settings already is like they suggest: ”AppStore and identified developers”.

https://secure.clcbio.com/helpspot/index.php?pg=kb.page&id=323

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Answer 4

torbjorn160 Author

Level 1

10 points

Feb 15, 2019 5:30 AM in response to Eric Root

I have just noticed that the system always revert to the setting: AppStore (only) in the preferences section Privacy & Integrity. No matter how many times I change it and lock the pad lock, the next time I open system preferences it's reverted to that setting.

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Answer 5

torbjorn160 Author

Level 1

10 points

Feb 15, 2019 12:54 PM in response to Eric Root

Now I have done according to your instructions, but the issues remains.

I recall that this occurred after I the latest Apple Security Update. I have no clue if there is any connection to it.

I think your theory of a corrupt .plist sounds very plausible, or maybe something similar, since the issue is a general one.

It has something to do with opening downloaded installers or files. But the files aren't damaged or corrupt, since they can be opened by other computers in my local network. They seem to be labelled as ”bad” at a core function of the system.

The ”smoking gun” is that weird App Store (only) preference.

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Answer 6

torbjorn160 Author

Level 1

10 points

Feb 17, 2019 12:23 AM in response to Eric Root

I didn't, but when I did, all went back to normal funktion. So this is what was needed:

Mac OS Sierra 10.12.x

If you view your security settings under System Preferences | Security & Privacy, you will see there is no Anywhere option.

To enable the "Anywhere" option, run the following command in a terminal:

sudo spctl --master-disable

If you go back to System Preferences | Security & Privacy, you will see the Anywhere option enabled. Unlock the edit option by clicking on the padlock icon at the bottom of the window to change to Anywhere option.

At this point, you should be able to install the software.

This security setting affects your whole system. To reinstate the earlier security policy, run the following after the software is installed: