Error messages: what they mean and how to fix
How to troubleshoot error messages on Firefox
- What does "Your connection is not secure" mean? When connecting to a website that uses an invalid TLS certificate or weak encryption, Firefox will display an error page saying "Your connection is not secure".
- How to troubleshoot the error code "SEC_ERROR_UNKNOWN_ISSUER" on secure websites This article explains why you might see the error code "SEC_ERROR_UNKNOWN_ISSUER" on HTTPS websites and how you can troubleshoot it.
- How to troubleshoot time related errors on secure websites This article explains why you might see time-related errors on HTTPS websites and how you can troubleshoot them by correcting your system clock.
- Troubleshoot the "Secure Connection Failed" error message If Firefox can't access a secure (https) site you'll get a "Secure Connection Failed" page. Learn the reasons this happens and what to do.
- 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.
- Certificate Pinning Reports Firefox certificate pinning reports; what they are and why you might want to share yours.
- 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.
- "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".
- 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.
- 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.
- How to allow Java on trusted sites Learn how to activate Java in Firefox, if necessary, and where to find info about Java prompts and "Application Blocked by Security Settings" error messages.
- 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 plugin - What it means and how to fix it This article describes the reasons for this error message and covers possible solutions and workarounds.
- 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.