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

Firefox cant find xpcom_core.dll. What do I do?

  • 1 reply
  • 20 have this problem
  • 4 views
  • Last reply by cor-el

more options

Whenever it boots up to my yahoo page error message "cant find xpcom_core.dll".

What do I do to fix this problem?

Whenever it boots up to my yahoo page error message "cant find xpcom_core.dll". What do I do to fix this problem?

All Replies (1)

more options

The file xpcom_core.dll was last used in Firefox 2.0.0.x versions and is no longer present in current Firefox versions.
You seem to have a program or an add-on that is still looking for that file.


Your plugins list shows that you have the Mozilla ActiveX plugin installed and that might cause your problem.
The Mozilla ActiveX plugin is not compatible with Firefox 2 and 3 and you should remove it.

For instructions on how to remove the Mozilla ActiveX plugin see: http://kb.mozillazine.org/ActiveX