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Error at start-up: JAVA Script what happened:TypeError: Components.classes['@mozilla.org/extensions/manager;1'] is undefined

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New User

Error at start-up: JAVA Script what happened:TypeError: Components.classes['@mozilla.org/extensions/manager;1'] is undefined

his message is displayed on Firefox start-up:

Box title is "JAVA Script Application"

what happened:TypeError: components.classes['@mozilla.org/extensions/manager;1'] is undefined

8 REPLIES
Support Forum Moderator

Re: Error at start-up: JAVA Script what happened:TypeError: Components.classes['@mozilla.org/extensions/manager;1'] is undefined

That is an indication that you have an incompatible add-on. Follow the procedure in the Troubleshoot extensions, themes and hardware acceleration issues to solve common Firefox problems article to identify the culprit.

New User

Re: Error at start-up: JAVA Script what happened:TypeError: Components.classes['@mozilla.org/extensions/manager;1'] is undefined

Foxit Toolbar is a likely suspect if you started receiving this message recently. The error stopped happening for me the instant I disabled this add-on.

Site Moderator

Re: Error at start-up: JAVA Script what happened:TypeError: Components.classes['@mozilla.org/extensions/manager;1'] is undefined

@ghosking

Your above posted system details show outdated plugin(s) with known security and stability risks.

  1. Shockwave Flash 10.0 r42
  2. Next Generation Java Plug-in 1.6.0_18 for Mozilla browsers

Update the Java plugin to the latest version.

Update the Flash plugin to the latest version.

Senior User
Senior User

Re: Error at start-up: JAVA Script what happened:TypeError: Components.classes['@mozilla.org/extensions/manager;1'] is undefined

This could also be caused by the Ask Toolbar. Can you disable that and try again?

Regular User

Re: Error at start-up: JAVA Script what happened:TypeError: Components.classes['@mozilla.org/extensions/manager;1'] is undefined

If you have the Ask Toolbar installed under Firefox 4.0b1+ it will give this error. The toolbar lies in its install manifest to say it is compatible with up to Firefox 5.* (you heard me) thus you'll need to disable or uninstall it. A blocklist request is pending...

New User

Re: Error at start-up: JAVA Script what happened:TypeError: Components.classes['@mozilla.org/extensions/manager;1'] is undefined

It happens to me when I installed a new release of skype (5.5). Yust disable the plugin and the problem will fixed.

New User

Re: Error at start-up: JAVA Script what happened:TypeError: Components.classes['@mozilla.org/extensions/manager;1'] is undefined

I concur that the problem is an add-on that is incompatible with FF5. Disable it and reboot. Problem solved.

New User

Re: Error at start-up: JAVA Script what happened:TypeError: Components.classes['@mozilla.org/extensions/manager;1'] is undefined

Thank u very much for your post, cuz u were right on the money! After chasing the problem for hours last nite, installing, uninstalling etc.; I stumbled across your post here thankfully. Thank u once again!