Join the AMA (Ask Me Anything) with the Firefox leadership team to celebrate Firefox 20th anniversary and discuss Firefox’s future on Mozilla Connect. Mark your calendar on Thursday, November 14, 18:00 - 20:00 UTC!

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

Error message when opening Firefox

more options

After a windows update I get the following message when I try to open Firefox: The procedure entry point ?ToLogLevel@mozilla@@VA?AW4LogLevel@1@H@Z could not be located in the dynamic link library C:ProgramFiles\Mozilla Firefox\xul.dll Then I get Couldn't load XPCOM

I tried uninstalling firefox but it just hung. I restored it to before the windows update but still got the same message

After a windows update I get the following message when I try to open Firefox: The procedure entry point ?ToLogLevel@mozilla@@VA?AW4LogLevel@1@H@Z could not be located in the dynamic link library C:ProgramFiles\Mozilla Firefox\xul.dll Then I get Couldn't load XPCOM I tried uninstalling firefox but it just hung. I restored it to before the windows update but still got the same message

Chosen solution

Try downloading and reinstalling Firefox on top of itself. I know the correct way is to uninstall a program then reinstall it. But since you can't uninstall it perhaps reinstalling it will fix the issue. What it looks like is that file xul.dll got damaged and can't load Firefox properly. Reinstalling Firefox should update that file to a undamaged condition.

Download it from here: https://download.mozilla.org/?product=firefox-latest-ssl&os=win64&lang=en-US

Read this answer in context 👍 0

All Replies (5)

more options

Chosen Solution

Try downloading and reinstalling Firefox on top of itself. I know the correct way is to uninstall a program then reinstall it. But since you can't uninstall it perhaps reinstalling it will fix the issue. What it looks like is that file xul.dll got damaged and can't load Firefox properly. Reinstalling Firefox should update that file to a undamaged condition.

Download it from here: https://download.mozilla.org/?product=firefox-latest-ssl&os=win64&lang=en-US

Helpful?

more options

This worked BUT I don't see it on my desktop so I can add it to my tool bar.

A separate question. When I go to yahoo mail in firefox I get Gah your tab just crashed and restore the tab doesn't work. In chrome I can go to yahoo mail.

Helpful?

more options

OK I figured out how to get an icon on my taskbar

Helpful?

more options

Great! So Firefox is working now and the last problem you have is the crash on the Yahoo Mail page?

Helpful?

more options

I restarted it and that solved my problem. Thank you for your help

Helpful?

Ask a question

You must log in to your account to reply to posts. Please start a new question, if you do not have an account yet.