Error messages: what they mean and how to fix
How to troubleshoot error messages on Firefox
- What do the security warning codes mean? Firefox shows you a warning page about a potential security risk when you try to connect to a secure site but your connection is not secure.
- "Firefox is already running but is not responding" error message - How to fix it How to start Firefox if you see an error message, "Firefox is already running, but is not responding" or, on Mac OS X, "A copy of Firefox is already open".
- 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.
- Firefox tab crashes with Quick Heal security software After the update to Firefox 63, some users with Quick Heal security software might be impacted by tabs repeatedly crashing. This article explains how to fix that.
- How to fix the Update Failed error message when updating Firefox This article presents solutions and workarounds to a failed Firefox update so that you can get it updated and working correctly again.
- Warning Unresponsive script - What it means and how to fix it This article describes the reasons for this error message and covers possible solutions and workarounds.
- Firefox says it's just updated every time it starts - how to fix If you see "Firefox Updated" or "You've been updated to the latest version of Firefox" every time you start Firefox, we'll show you how to fix it.
- Warning Unresponsive plugin - What it means and how to fix it This article describes the reasons for this error message and covers possible solutions and workarounds.
- Fix "The bookmarks and history system will not be functional" error message This article explains what to do if you see the error message "The bookmarks and history system will not be functional" when you start Firefox.
- File system paths on Linux are always treated as UTF-8 On Linux, the profile path is required to be valid UTF-8. Names of downloaded files are encoded in UTF-8 regardless of glibc and glib settings.
- Certificate Pinning Reports Firefox certificate pinning reports; what they are and why you might want to share yours.
- 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.
- Certificate contains the same serial number as another certificate Why Firefox may show you a Secure Connection Failed error when you try to access the configuration page for your router and what to do.
- What do the SSLv3 error messages mean on Firefox? When accessing a site with SSLv3, Firefox will block it and display an "Unable to connect securely" message.
- How to troubleshoot time related errors on secure websites Learn why you might see time-related errors on HTTPS websites and how you can troubleshoot these errors by correcting your system clock.
- How to Disable the Enterprise Roots Preference This article explains how to disable the Enterprise Roots preference without compromising security.
- How to run Firefox when your profile is missing or inaccessible How to fix the error ''Your Firefox profile cannot be loaded. It may be missing or inaccessible'' so that you can start and run Firefox.