Join the AMA (Ask Me Anything) with the Firefox leadership team to celebrate Firefox 20th anniversary and discuss Firefox’s future on Mozilla Connect. Mark your calendar on Thursday, November 14, 18:00 - 20:00 UTC!

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

I installed Firefox 3.0.5 now every time I start it, I first get an JavaScript Application error message that says "TypeError: Components.classescid is undefined". I also get this message if I click a link inside an active window that opens a new window.

  • 1 பதிலளி
  • 2 இந்த பிரச்னைகள் உள்ளது
  • 9 views
  • Last reply by Morbus

I installed Firefox 3.0.5 now every time I start it, I first get an JavaScript Application error message that says "TypeError: Components.classescid is undefined". I also get this message if I click a link inside an active window that opens a new window. Firefox seems to work fine once I click "OK" in the error message window, but can anyone tell me how to fix it so I stop getting this error?

This happened

Every time Firefox opened

== i open firefox

I installed Firefox 3.0.5 now every time I start it, I first get an JavaScript Application error message that says "TypeError: Components.classescid is undefined". I also get this message if I click a link inside an active window that opens a new window. Firefox seems to work fine once I click "OK" in the error message window, but can anyone tell me how to fix it so I stop getting this error? == This happened == Every time Firefox opened == i open firefox

All Replies (1)

Hello Angelika.

I should bring your attention to the fact that your user agent says you're using Firefox 3.6, not 3.0. I will remind you that Firefox 3.0 has been discontinued and is no longer supported. Furthermore, it has known bugs and security problems.

As for your problem, you may be having a problem with some Firefox add-on that is hindering your Firefox's normal behavior. Have you tried disabling all add-ons (just to check), to see if Firefox goes back to normal?

Whenever you have a problem with Firefox, whatever it is, you should make sure it's not coming from one of your installed add-ons, be it an extension, a theme or a plugin. To do that easily and cleanly, run Firefox in safe mode and select Disable all add-ons. If the problem disappears, you know it's from an add-on. Disable them all in normal mode, and enable them one at a time until you find the source of the problem. See this article for information about troubleshooting extensions and theme. You can troubleshoot plugins the same way.

If you want support for one of your add-ons, you'll need to contact its author.