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.
Last updated: 03/21/2024
Captive portal detection
Description of how Firefox detects captive portal networks.
Last updated: 01/10/2024
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.
Last updated: 07/27/2023
Connection settings in Firefox
Your organization or Internet Service Provider may offer or require you to use a proxy to connect to the Internet. Learn more.
Last updated: 11/18/2023
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.
Last updated: 09/11/2023
Firefox can't load websites but other browsers can
We'll explain errors such as "Server not found" or "Unable to connect" and how to fix problems where Firefox can't access websites but other browsers can.
Last updated: 07/07/2022
How to let Firefox use the internet on your Windows computer
A "Server not found" error can be caused by Windows Firewall blocking Firefox from accessing the Internet. Learn how to configure it to allow Firefox access.
Last updated: 02/19/2022
Server Not Found - Troubleshoot connection problems
If you can't connect to a website, you may see the Server Not Found error message. Learn how to troubleshoot and fix this error.
Last updated: 10/22/2022
How to resolve weak crypto error messages on Firefox
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".
Created: 11/09/2015
