Search Support

Avoid support scams. We will never ask you to call or text a phone number or share personal information. Please report suspicious activity using the “Report Abuse” option.

Learn More

I keep receiving this message when I run mozilla firefox for win7 "what happened:TypeError: Components.classes['@mozilla.org/extensions/manager;1'] is undefined"

  • 3 cavab
  • 48 have this problem
  • 1 view
  • Last reply by cor-el

more options

Whenever I open Firefox... an error pop up window appears with this message "what happened:TypeError: Components.classes['@mozilla.org/extensions/manager;1'] is undefined"

Whenever I open Firefox... an error pop up window appears with this message "what happened:TypeError: Components.classes['@mozilla.org/extensions/manager;1'] is undefined"

Chosen solution

This issue can be caused by an extension that isn't working properly.

Start Firefox in Diagnose Firefox issues using Troubleshoot Mode to check if one of the extensions is causing the problem (switch to the DEFAULT theme: Firefox (Tools) > Add-ons > Appearance/Themes).

If it does work in Safe-mode then disable all extensions and then try to find which is causing it by enabling one at a time until the problem reappears.

  • Use "Disable all add-ons" on the Safe mode start window to disable all extensions.
  • Close and restart Firefox after each change via "File > Exit" (Mac: "Firefox > Quit"; Linux: "File > Quit")

In Firefox 4 you can use one of these to start in Safe mode:

  • Help > Restart with Add-ons Disabled
  • Hold down the Shift key while double clicking the Firefox desktop shortcut (Windows)

Read this answer in context 👍 5

All Replies (3)

more options

Seçilmiş Həll

This issue can be caused by an extension that isn't working properly.

Start Firefox in Diagnose Firefox issues using Troubleshoot Mode to check if one of the extensions is causing the problem (switch to the DEFAULT theme: Firefox (Tools) > Add-ons > Appearance/Themes).

If it does work in Safe-mode then disable all extensions and then try to find which is causing it by enabling one at a time until the problem reappears.

  • Use "Disable all add-ons" on the Safe mode start window to disable all extensions.
  • Close and restart Firefox after each change via "File > Exit" (Mac: "Firefox > Quit"; Linux: "File > Quit")

In Firefox 4 you can use one of these to start in Safe mode:

  • Help > Restart with Add-ons Disabled
  • Hold down the Shift key while double clicking the Firefox desktop shortcut (Windows)

more options

Many thanks. It's solved. Cheers!

more options

You're welcome