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The following error message came when I tried to open Firefox and install Firefox Home. "can't create mcafee plug-in object: TypeError: Components.classes[cid] is undefined"

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  • Last reply by cor-el

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The following error message came when I tried to open Firefox and install Firefox Home.

"can't create mcafee plug-in object: TypeError: Components.classes[cid] is undefined"

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This issue can be caused by an extension or plugin that isn't working properly.

Start Firefox in Troubleshoot Firefox issues using Safe Mode to check if one of the add-ons is causing the problem (switch to the DEFAULT theme: Tools > Add-ons > Themes).

  • Don't make any changes on the Safe mode start window.

See:

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This error is caused (in my case) by the McAfee SiteAdvisor plug-in. I have recently sent in a support request and will post the results here in approx. 48 hours unless they respond sooner. In the meantime disable this add-on/plug-in and FF 4 will work fine. Also be careful when surfing the web without a link checker!