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".
- Troubleshoot the "Secure Connection Failed" error message If Firefox can't access a secure (https) site you'll get a "Secure Connection Failed" page. We'll explain the reasons for this and how to fix or bypass it.
- 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.
- 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.
- 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.
- "This Connection is Untrusted" error message appears - What to do This article explains what this error message means and how to bypass the warning in Firefox if you need to.
- 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.
- 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.
- Unable to access secure (HTTPS) sites in Firefox 43 This article explains how to fix the error SEC_ERROR_CERT_SIGNATURE_ALGORITHM_DISABLED so you can access secure (HTTPS) sites in Firefox 43.
- "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".
- 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.
- 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.
- 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.