Performance and connectivity
Deal with error messages, crashing applications, connectivity issues, and slow performance.
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.
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Captive portal detection
Description of how Firefox detects captive portal networks.
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3 weeks ago
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.
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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.
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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.
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Manage the devices linked to your Mozilla account
Find solutions to help you manage the devices and services connected to your Mozilla account.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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Connecting to unsecured networks while using Mozilla VPN
Mozilla VPN will alert you if you're connecting to an unsecured network.
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Search your browsing history in Firefox for iOS
You can search your browsing history within the History panel in Firefox for iOS.
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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.
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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".
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What is the Mozilla VPN kill switch?
This page explains a what a kill switch is
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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.
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Fritz!box isn't working when Mozilla VPN is on
Fritz!box is blocked when Mozilla VPN is on.
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Exclude applications from Mozilla VPN protection
Exclude applications from Mozilla VPN protection
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Resist Fingerprinting
Resist Fingerprinting in Firefox limits the personal characteristics of the operating system and hardware exposed to websites
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1 week, 3 days ago
Address screen sharing issues with Firefox on macOS 15 Sequoia
Learn how to resolve screen sharing issues in Firefox when using macOS 15 'Sequoia' due to changes in Apple's API.
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2 days, 20 hours ago
