Scheduled maintenance: Thursday, September 24, between 11:30am and 13:30pm 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

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

Javascript pop errors stating: TypeError: Components.classes[cid] is undefined

  • 18 replies
  • 2388 have this problem
  • 4772 views
  • Last reply by mluna

more options

Javascript Application pop up error on website load after page is loaded saying : TypeError: Components.classes[cid] is undefined I run an HP Pavilion dv5 on Windows Vista

This happened

Every time Firefox opened

== I first started using Firefox

Chosen solution

Start Firefox in Troubleshoot Firefox issues using Safe Mode to check if one of your add-ons is causing your problem (switch to the DEFAULT theme: Tools > Add-ons > Themes). See Troubleshoot extensions, themes and hardware acceleration issues to solve common Firefox problems and Troubleshoot issues with plugins like Flash or Java to fix common Firefox problems

If it does work in Safe-mode then disable all your extensions and then try to find which is causing it by enabling one at a time until the problem reappears. You can use "Disable all add-ons" on the Troubleshoot Firefox issues using Safe Mode start window to disable all extensions. You have to close and restart Firefox after each change via "File > Exit" (Mac: "Firefox > Quit"; Linux: "File > Quit")

Read this answer in context 👍 33

All Replies (18)

more options

Chosen Solution

Start Firefox in Troubleshoot Firefox issues using Safe Mode to check if one of your add-ons is causing your problem (switch to the DEFAULT theme: Tools > Add-ons > Themes). See Troubleshoot extensions, themes and hardware acceleration issues to solve common Firefox problems and Troubleshoot issues with plugins like Flash or Java to fix common Firefox problems

If it does work in Safe-mode then disable all your extensions and then try to find which is causing it by enabling one at a time until the problem reappears. You can use "Disable all add-ons" on the Troubleshoot Firefox issues using Safe Mode start window to disable all extensions. You have to close and restart Firefox after each change via "File > Exit" (Mac: "Firefox > Quit"; Linux: "File > Quit")

more options

you rock dude thank god this worked I was getting to the point of yelling at my computer because of the pop ups were getting worse! you rock thanks for helping me! :^D

more options

So...what were the offending add-ons?

more options

This really does work. I select Disable all add0ons, then I will start enabling one by one until I find the issue. I will try to remember to add a comment once I find it!

more options

It was some older add-ons that caused this problem. Once you select disable add-ons, you will see which are not supported by 4.0 Beta 2. Just remove and restart. Then enable each one one at time and restart.

Hope this helps!

more options

I got it to go away by (as someone already said) disabling all the add-ons and then enabling them one by one. The ones that were the problems were called 'Context Management Controller 2.8.0.4360' and 'Textual Media Service 2.8.0.4580'. I hope this helps.

more options

This fixed my issue, disabled all add-ons. Turned out to be the telephony toolbar that our new voip system installed.

more options

I found that the culprit for me was Zonealarm. FF Works like a charm with this disabled.

Michael Nunneley Post Falls ID

more options

I found that the culprit was eSnips downloader toolbar.

more options

GuardedID Toolbar 3.0 (Provided by Trend Micro) is the problem for my error of this type.

more options

I have the same problem. I disabled all the Add-Ons and restarted Firefox, but the problem doesn't go away. I even reinstalled Firefox 4 and applied the newest java. Still no luck.

more options

Have also got TypeError: Components.classes[cid] is undefined a Java script issue on latest version of Mozilla, am beginning to think there are corrupt files as also cannot access "Menu" toolbar although it shows briefly if I go to "customise" then "Restore default set" but promptly disappears when I close that tool. I have several toolbars selected (Right click on blank area at top of Firefox window) but they can't be deselected. I can't go into Safe mode and have tried uninstalling and reinstalling but to no avail.

Anyone got any ideas what to try next?

more options

For the toolbars (customize) problem see:


Create a new profile as a test to check if your current profile is causing the problems.

See:

There may be extensions and plugins installed by default in a new profile, so check that in "Tools > Add-ons > Extensions & Plugins"

If that new profile works then you can transfer some files from the old profile to that new profile (be careful not to copy corrupted files)

See:

more options

quicknote 0.6.0.8 was my problem. disabled and removed. problem solved.

more options

On my laptop, the culprit was "OneClick YouTube Downloader", version 1.0.6. I believe it came with Orbit Downloader, a standalone app. Once I disabled this addon, the error went away.

more options

another update....another new problem!

why don't you guys slow down a bit & test this stuff out before you release it??!!

i'd love to see which add on might be the culprit, but firefox won't load the page with my add ons...

any comment?

more options

I agree. This problem has continued to bug me for a couple of weeks now. I cannot uninstall my plug-ins, as some of them act as virus protection (noScript)...others I use constantly. This is the first time I've had an issue with FF. HURRY UP AND MAKE ANOTHER VERSION. I tried to reinstall it to no avail. Apparently this error is common with this release. Next step for me will be to find a lower version release - 9 maybe...

more options

Locking this post, please start a new thread if you need additional help.

-Michelle