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after updating to latest version, Firefox won't open

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  • 6 have this problem
  • 4 views
  • Last reply by cor-el

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I am running Windows 7. After updating to the latest version, Firefox won't open. I get a notice when I try to open Firefox saying "Couldn't load XPCOM. Is there a way I can undo the update so I can get Firefox to open. It's my favorite browser...I'm having to use another browser to ask my question.

I am running Windows 7. After updating to the latest version, Firefox won't open. I get a notice when I try to open Firefox saying "Couldn't load XPCOM. Is there a way I can undo the update so I can get Firefox to open. It's my favorite browser...I'm having to use another browser to ask my question.

Modified by netbookmary

Chosen solution

Do a clean reinstall and delete the Firefox program folder before (re)installing a fresh copy of the current Firefox release.

Download a fresh Firefox copy and save the file to the desktop.

Uninstall your current Firefox version, if possible, to cleanup the Windows registry and settings in security software.

  • Do NOT remove personal data when you uninstall your current Firefox version, because all profile folders will be removed and you lose personal data like bookmarks and passwords from profiles of other Firefox versions.

Remove the Firefox program folder before installing that newly downloaded copy of the Firefox installer.

  • (32 bit Windows) "C:\Program Files\Mozilla Firefox\"
  • (64 bit Windows) "C:\Program Files (x86)\Mozilla Firefox\"

Your bookmarks and other personal data are stored in the Firefox profile folder and won't be affected by an uninstall and (re)install, but make sure that "remove personal data" is NOT selected when you uninstall Firefox.


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It is often because security related software does not recognise the new browser.

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Chosen Solution

Do a clean reinstall and delete the Firefox program folder before (re)installing a fresh copy of the current Firefox release.

Download a fresh Firefox copy and save the file to the desktop.

Uninstall your current Firefox version, if possible, to cleanup the Windows registry and settings in security software.

  • Do NOT remove personal data when you uninstall your current Firefox version, because all profile folders will be removed and you lose personal data like bookmarks and passwords from profiles of other Firefox versions.

Remove the Firefox program folder before installing that newly downloaded copy of the Firefox installer.

  • (32 bit Windows) "C:\Program Files\Mozilla Firefox\"
  • (64 bit Windows) "C:\Program Files (x86)\Mozilla Firefox\"

Your bookmarks and other personal data are stored in the Firefox profile folder and won't be affected by an uninstall and (re)install, but make sure that "remove personal data" is NOT selected when you uninstall Firefox.