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I can't get Firefox to start at all on my Mac. I've updated my system, uninstalled & reinstalled multiple times, and deleted my profile. Fix?

  • 9 uphendule
  • 2 zinale nkinga
  • Igcine ukuphendulwa ngu Cyndaquil

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As the question says. I updated my Mac (2018 MacBook Pro) to the most recent OS (Catalina), I've uninstalled and reinstalled Firefox like 6 times, cleared my trash and any and all Firefox files, and deleted all profiles, made a new default one, and then deleted that one when it still wouldn't start, and restarted my laptop more than once. I cannot seem to get it to start no matter what I do! I've tried every fix I can find online. Every time I try to launch Firefox, it appears in the dash for a second and immediately shuts down. Trying to start in Safe Mode doesn't work either. Firefox used to work, but then I force quit it *once* because I was quitting all applications I wasn't using. Now it won't work at all no matter what I do. How do I fix this?

All Replies (9)

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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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I don't have any firewall enabled or any Internet security software, so there's nothing to change or remove. I don't think this is the problem, but thank you.

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Start your Computer in safe mode with network support. Then start Firefox. Try Secure websites. Is the problem still there? Starting Any Computer In Safe Mode; Free Online Encyclopedia

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I started my Mac in safe mode and tried to start Firefox, but I got the same error--the application shut down the second I opened it. I wasn't able to try any secure websites because of that.

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I called for more help.

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Was anyone able to give any advice?

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Hi Cyndaquil:

Please try running a Mac malware scanner like malwarebytes to see if you have malware on your system. FF74 works fine on my two Macs running OS X 10.15 Catalina and for many other Catalina users.



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Can you start Firefox via a terminal window to see if you get possible error messages displayed ?

Mac HD -> Applications -> Utilities -> Terminal
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I was able to get it to work for a couple days by installing the Beta version of the browser, but as soon as I quit that application, it started refusing to open. Now I can't get any version to work no matter which I download. I already wiped my profiles again, and restarted and removed everything Firefox from my files and then emptied my trash. I still can't get it to work all over again. Roland Tanglao--I installed and ran malwarebytes free, and the scanner detected nothing. core-el--I started Terminal and entered that, but got a message saying "no such file or directory" even when I had Firefox installed and had tried to start it.