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Every time I try to open the .dmg to install XQuartz, a window pops up saying the following disk images couldn't be opened and the reason shown is not recognized. I don't know if I need another application to open it or if the file is corrupted, or if it's some other problem entirely.

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Are you on Mountain Lion? is gatekeeper on? – user1256923 Nov 20 '12 at 11:06

I'd say the file downloaded is corrupted, you should be able to open the .dmg by simply double clicking it (I downloaded XQuartz a couple of days ago and could open the .dmg without a problem).

Unfortunately, the download page doesn't provide a checksum to check against, so I'll provide the one I generated:


This checksum uniquely identifies the XQuarz .dmg.

You can generate a checksum of XQuartz on your Mac like this (from

  1. Open Terminal (in /Application/Utilities)
  2. Type:

    openssl sha1 ~/Downloads/XQuartz-2.7.4.dmg

    (adapt to the path where XQuartz-2.7.4.dmg was downloaded)

  3. Compare the number you get with the number above. If they are different, the file is corrupted.
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