This site will have limited functionality while we undergo maintenance to improve your experience. If an article doesn't solve your issue and you want to ask a question, we have our support community waiting to help you at @FirefoxSupport on Twitter and/r/firefox on Reddit.

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

There is error message when start Firefox 4.0.1 as follow: "what happened: TypeError; Components.classes['@mozzilla.org/extensions/manager;1'] is undefined"

  • 1 reply
  • 2 have this problem
  • 4 views
  • Last reply by TonyE

more options

There is error message when start Firefox 4.0.1 as follow: "what happened: TypeError; Components.classes['@mozzilla.org/extensions/manager;1'] is undefined"

There is error message when start Firefox 4.0.1 as follow: "what happened: TypeError; Components.classes['@mozzilla.org/extensions/manager;1'] is undefined"

All Replies (1)

more options

That indicates that you are using an add-on that is not compatible with Firefox 4. For details of how to troubleshoot this to find out what one is causing the problem see https://support.mozilla.com/kb/Troubleshooting+extensions+and+themes