Performance and connectivity

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: 3/21/24

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: 7/27/23

Captive portal detection

Description of how Firefox detects captive portal networks.

Last updated: 2 weeks ago

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: 9/11/23

Firefox blocked by macOS 15 Sequoia firewall - What you need to know

Some macOS 15 users may have Firefox blocked by the firewall. Learn about the issue and how to help Mozilla investigate.

Last updated: 9/24/24

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: 3 weeks, 3 days ago

Manage the devices linked to your Mozilla account

Find solutions to help you manage the devices and services connected to your Mozilla account.

Last updated: 10/29/23

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: 2/19/22

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: 7/7/22

Disable Firefox Sync

Learn how to turn off Firefox Sync if you’d like to use your Mozilla account without syncing data such as, bookmarks, history and tabs.

Last updated: 10/30/23

Multi-Hop - Encrypt your data twice for enhanced security while using Mozilla VPN

Add an extra layer of protection to your data using multiple servers on Mozilla VPN.

Last updated: 4/2/24

Browsing history in Firefox - View the websites you have visited

Firefox keeps track of the websites you visit when you browse the Web. Learn how to view, search and sort your browsing history.

Last updated: 9/22/23

Connecting to unsecured networks while using Mozilla VPN

Mozilla VPN will alert you if you're connecting to an unsecured network.

Last updated: 4/13/22

Resist Fingerprinting

Resist Fingerprinting in Firefox limits the personal characteristics of the operating system and hardware exposed to websites

Last updated: 1 week, 3 days ago

Using a Primary Password with Sync

Learn how to use Sync in Firefox with a Primary Password (formerly known as a “Master Password”) for extra protection.

Last updated: 3/19/24

Search your browsing history in Firefox for iOS

You can search your browsing history within the History panel in Firefox for iOS.

Last updated: 7/22/22

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: 10/22/22

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: 11/9/15

What is the Mozilla VPN kill switch?

This page explains a what a kill switch is

Last updated: 3/22/23

Joining public WiFi while on Mozilla VPN

How to get online if you have trouble connecting to the Internet on public WiFi while on Mozilla VPN.

Last updated: 4/5/24

Fritz!box isn't working when Mozilla VPN is on

Fritz!box is blocked when Mozilla VPN is on.