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Windows 10 reached EOS (end of support) on October 14, 2025. For more information, see this article.

Performance and connectivity

Error codes

Troubleshoot issues with error codes.

In English

Secure connection and security warning error pages in Firefox

Fix "The bookmarks and history system will not be functional" error message

Fix error “Website will not allow Firefox to display the page.”

Warning Unresponsive script - What it means and how to fix it

Certificate contains the same serial number as another certificate

What do the security warning codes mean?

"Firefox is already running but is not responding" error - How to fix

How to fix the Update Failed error message when updating Firefox

Solutions for "Can not create temp folder archive" error when installing Firefox (Windows 10)

Websites say that Firefox is outdated or incompatible even though it's the latest version

Firefox says it's just updated every time it starts - how to fix

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