We're calling on all EU-based Mozillians with iOS or iPadOS devices to help us monitor Apple’s new browser choice screens. Join the effort to hold Big Tech to account!

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

Cuireadh an snáithe seo sa chartlann. Cuir ceist nua má tá cabhair uait.

When I open Firefox, the browser does not open. Instead I get a small window that says: TypeError: Components.classes[cid] is undefined. How do I fix this?

more options

I tried to uninstall AVG antiviral software, but it did not uninstall. Next, when I try to open Firefox I get a box popup that says:

TypeError: Components.classes[cid] is undefined.

If I click OK in that box, I can then open Firefox.

Also I can no longer update Java.

Help!

I tried to uninstall AVG antiviral software, but it did not uninstall. Next, when I try to open Firefox I get a box popup that says: TypeError: Components.classes[cid] is undefined. If I click OK in that box, I can then open Firefox. Also I can no longer update Java. Help!

All Replies (2)

more options

Start Firefox in Diagnose Firefox issues using Troubleshoot Mode to check if one of the extensions or if hardware acceleration is causing the problem (switch to the DEFAULT theme: Firefox (Tools) > Add-ons > Appearance/Themes).

more options

Possibly you have "AVG Safe search" extension installed as part of "AVG Free", solution involves reinstalling :AVG Free" without the Link Scanner component see

Other possibilities

If none of the above solve you problem use diagnostic approach...

Athraithe ag David McRitchie ar