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Updated to Mac Sierra, now Firefox will not open.

  • 5 ردود
  • 1 has this problem
  • 21 views
  • آخر ردّ كتبه FredMcD

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Firefox browser worked perfectly with my iMac 27" with Snow Leopard. After upgrading to Sierra 10.12, Firefox will not open. I downloaded and installed the latest version of Firefox from your site, which states that it will automatically determine compatibility with my operating system.

Interestingly, when I click on Firefox, there is no response, no "Firefox" on the top left of the screen next to the small Apple logo, and no Firefox page, nota. Yet when I bring up the "Force Quit" box, Firefox is listed as if it is open and you can click on it to make it "quit".

BTW, Google Chrome and Safari are working perfectly with Sierra.

Please help me get my Firefox back. Thanks,

All Replies (5)

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Some problems occur when your Internet security program was set to trust the previous version of Firefox, but no longer recognizes your updated version as trusted. Now how to fix the problem: To allow Firefox to connect to the Internet again;

  • Make sure your Internet security software is up-to-date (i.e. you are running the latest version).
  • Remove Firefox from your program's list of trusted or recognized programs. For detailed instructions, see

Configure firewalls so that Firefox can access the Internet. {web link}

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Fred, thank you for your response. I followed your instructions, but the situation remains unchanged. Firefox will still not open.

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Let’s do a full clean re-install; Download Firefox For All languages And Systems {web link} Save the file. Then Close Firefox.

Using your file browser, open the Programs Folder on your computer.

Windows: C:\Program Files C:\Program Files (x86) Mac: Open the "Applications" folder.
https://support.mozilla.org/en-US/kb/how-download-and-install-firefox-mac Linux: Check your user manual. If you installed Firefox with the distro-based package manager, you should use the same way to uninstall it - see Install Firefox on Linux. If you downloaded and installed the binary package from the Firefox download page, simply remove the folder Firefox in your home directory.

Do Not remove the profiles folder.

Look for, and rename any Mozilla or Firefox program folders by adding .old to them. Do not rename the Mozilla Thunderbird folder if there is one.

After rebooting the computer, run a registry scanner. Then run the installer. If all goes well, remove the OLD folders when you are done.


If there is a problem, start your Computer in safe mode and try again.

Starting The Computer In Safe Mode;
Free Online Encyclopedia

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Thanks again. I went through the steps you provided, but the situation is still as I described in my original post. Very frustrating.

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I've called for more help.

Start Firefox in Safe Mode {web Link} by holding down the <Shift>
(Mac=Options)
key, and then starting Firefox. A small dialog should appear. Click Start In Safe Mode (not Refresh).

Is the problem still there?


Start your Computer in safe mode with networking. Then start Firefox. Try Safe websites. Is the problem still there?

Starting The Computer In Safe Mode;
Free Online Encyclopedia