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Secure connection failed and Firefox did not connect
If a website requires a secure connection that cannot be established, Firefox will not connect and will show you an error page. Learn more.
How to troubleshoot security error codes on secure websites
Learn about the error codes SEC_ERROR_UNKNOWN_ISSUER MOZILLA_PKIX_ERROR_MITM_DETECTED and ERROR_SELF_SIGNED_CERT on HTTPS websites and how to troubleshoot.
Enhanced Tracking Protection in Firefox for desktop
Enhanced Tracking Protection in Firefox automatically protects your privacy while you browse.
Update Firefox to the latest release
Firefox automatically updates itself by default, but you can always do a manual update. Learn how to update Firefox on Windows, Mac, or Linux.
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