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Firefox worked until yesterday, but won't start

  • 4 replies
  • 1 has this problem
  • 5 views
  • Last reply by philipp

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Tried the suggestion in "https://support.mozilla.org/en-US/kb/firefox-wont-start-find-solutions#w_firefox-previously-worked" but still stuck

All Replies (4)

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Some problems occurs 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}


Start Firefox in Safe Mode {web Link} by holding down the <Shift (Mac Options) > key, and then starting Firefox. Is the problem still there?

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Hi, Thanks for the response. Tried the suggested actions and started Firefox in safe mode, but the problem still persists. Going to give it another go today and will get back to you if it works or not. Thanks once again!

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It is possible that your security software (firewall, anti-virus) blocks or restricts Firefox or the plugin-container process without informing you, possibly after detecting changes (update) to the Firefox program.

Remove all rules for Firefox and the plugin-container from the permissions list in the firewall and let your firewall ask again for permission to get full, unrestricted, access to install for Firefox and the plugin-container process and the updater process.

See:

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often adware & malware is prohibiting firefox to start properly. please run a full scan of your system with different security tools like the free version of malwarebytes and adwcleaner.

Troubleshoot Firefox issues caused by malware