If Firefox can't access a secure site (one that starts with https) you will see an error page with the heading Secure Connection Failed and a message about the error.

• If you see this heading without accessing a secure site, see Troubleshoot extensions, themes and hardware acceleration issues to solve common Firefox problems.
• If you see the error message Your connection is not secure, see the article What do the security warning codes mean?.
• For troubleshooting other error messages, see Websites don't load - troubleshoot and fix error messages.

Secure connection cannot be established

When a website you visit attempts to secure communication between your computer and the website, Firefox cross-checks this attempt to ensure that the certificate and the method the website is using are actually secure. If Firefox cannot establish a secure connection, you will see an error page similar to the one shown below, with a description of the error and an option to report the error to Mozilla:

Website issues

Some websites try using out-dated (no longer secure) TLS mechanisms in an attempt to secure your connection. Firefox protects you by preventing navigation to such sites if there is a problem in securely establishing a connection. When this happens, you will see a the Secure Connection Failed error page. If you experience this problem, contact the owners of the website and ask them to update their TLS version to a version that is still current and still secure.

Security software conflict

AVAST and AVG security products

If you use security products by Avast or AVG, they may be intercepting secure connections by default. These security products might not be ready for the most recent and secure TLS 1.3 specification that Firefox is generally rolling out in version 61 of the browser.

As a result, affected users of Avast or AVG security products may be seeing intermittent Secure Connection Failed error pages with the error code SSL_ERROR_RX_RECORD_TOO_LONG on secure websites like Google and others. As a workaround, affected users should disable the interception of secure connections in their security product:

1. Open the dashboard of your Avast or AVG application.
2. Go to Menu > Settings > Components and click Customize next to Web Shield.
3. Uncheck the Enable HTTPS Scanning setting and confirm this by clicking OK.

For more information, see Managing HTTPS scanning in Web Shield in Avast Antivirus on theAvast support site.

ESET and NOD32 security products

If you use an ESET security product such as NOD32 Antivirus or ESET Internet Security, turning off one of the following settings and then turning it back on may help eliminate the error.

• Enable application protocol content filtering
• Enable SSL/TLS protocol filtering

For detailed instructions, see this AskVG.com article. If you have questions or concerns about modifying these settings, please visit ESET support.

Certificate warnings

Firefox uses certificates on secure websites to ensure that your information is being sent to the intended recipient and can't be read by eavesdroppers. For a list of certificate warnings and error codes, see the article What do the security warning codes mean?.

Incorrect date settings

If the date is not correct on your system, this can cause Firefox to detect that the website's security certificate is expired or invalid. You should ensure that your system clock is set to today's date and time (double-click the clock icon on the Windows Taskbar). For information, see the article How to troubleshoot time related errors on secure websites.