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Since upgrading to 6 I get "TypeError: Components.classes[cid] is undefined" when loading Firefox - why?

  • 2 replies
  • 5 have this problem
  • 4 views
  • Last reply by dkjbateman

dkjbateman
dkjbateman
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When loading Firefox or certain pages I get a message box appear with "TypeError: Components.classes[cid] is undefined" if I hit "OK" the system continues. This has only happened since the recent security upgrade to Firefox. I have downloaded Firefox and reinstalled but the message persists.

When loading Firefox or certain pages I get a message box appear with "TypeError: Components.classes[cid] is undefined" if I hit "OK" the system continues. This has only happened since the recent security upgrade to Firefox. I have downloaded Firefox and reinstalled but the message persists.

All Replies (2)

cor-el
cor-el
  • Top 25 Contributor
  • Moderator
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This issue can be caused by an extension that isn't working properly.

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).

dkjbateman
dkjbateman Question owner
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Thanks traced it to "appearance" switched it to default and problem has gone away.