I just experienced this issue described in this answer.

I had downloaded a zip file containing a macOS app, and first unzipped it with Archive Utility, when trying to open the app, I got the error that it "could not be opened" (with no further clarification) just like in the Q&A linked to above.

However, when I used Keka (third party archive software) to unzip, the app worked just fine.

What is the technical explanation for this? Aren't zips and other archives supposed to come out literally the same, byte for byte? How can one unarchiver break the app, but not the other?

I use Catalina on an Intel Mac.

  • 2
    Did you compare/diff the outcome of the unzipped file between the two methods? Perhaps that will give some pointers on what is different? I suspect Archive Utility (un)sets some attribute which makes the file unusable. Nov 28, 2021 at 14:54

1 Answer 1


The file attributes are not the data that's stored in files, it's the information stored in the file system. Different archiving utilities may interpret information differently. It's either:

a) File attributes before zipping are incorrect and (some) unzipping utility fixes it
b) Unzipping utility has a bug.

I checked the archive with tar utility (widely used and well know utility). The file "Neuron.app/Contents/MacOS/Neutron" has no "x" attribute in it. The app creator probably forgot to set that attribute, so basically it's cause a).

  • 4
    Archive Utility is going to apply quarantine flags, other archivers most likely do not. I would check the .app bundle to see if that was applied. Nov 28, 2021 at 15:14
  • 2
    Their are reasons why.apps are distributed on compressed images. Ie dmg files
    – mmmmmm
    Nov 28, 2021 at 16:18

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