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

when I open Firefox, I get following message, "Java Script Application Type Error: Components. classes (cid) is undefined. What's wrong?

  • 1 ŋuɖoɖo
  • 3 masɔmasɔ sia le wosi
  • 1 view
  • Nuɖoɖo mlɔetɔ cor-el

more options

After a system restore and downloading of Firefox, every time I open Firefox, I get error message; Java Script Application Type Error: Components.classes (cid) is undefined. I am able to get rid of error message by clicking on close.

After a system restore and downloading of Firefox, every time I open Firefox, I get error message; Java Script Application Type Error: Components.classes (cid) is undefined. I am able to get rid of error message by clicking on close.

All Replies (1)

more options

This issue can be caused by an AVG extension.

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).