Performance and connectivity
Deal with error messages, crashing applications, connectivity issues, and slow performance.
Captive portal detection
Description of how Firefox detects captive portal networks.
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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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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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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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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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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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1 week, 5 days ago
Mozilla VPN won’t connect or keeps disconnecting - How to fix
What to do if Mozilla VPN disconnects or turns off after being activated, or if websites fail to load even though Mozilla VPN is connected.
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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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Resist Fingerprinting
Firefox's Advanced Preferences to resist fingerprinting can help prevent websites from uniquely identifying your device but can cause problems. Learn more.
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3 weeks, 1 day ago
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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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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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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Report Site Issues on Firefox for iOS
Learn how to report website issues or problems in Firefox for iOS.
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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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1 week ago
How can I tell if Mozilla VPN is connected?
Mozilla VPN displays visual indicators of its current status, making it easy to know whether your online activity is protected or not.
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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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Certificate warnings in Firefox for iOS
How to bypass certificate warnings in Firefox for iOS
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Firefox DNS over HTTPS
DoH improves privacy by hiding domain name lookups from anyone lurking on public Wi-Fi, your ISP or others on your local network. Learn more.
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1 week, 5 days ago
DNS over HTTPS (DoH) FAQs
We have outlined a list of FAQs here that you may find helpful while getting up to speed with all that DNS over HTTPS (DoH) has to offer.
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1 week, 5 days ago
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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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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How to obtain the Mozilla VPN Logs
When troubleshooting issues with Mozilla VPN, our engineers can ask for logs. These don't contain any personal information, but give hints about the issue.
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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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Firefox for iOS won't load web pages
If a website isn’t loading even after you’ve checked the Internet connection, here are a few things you can try.
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Exclude applications from Mozilla VPN protection
Exclude applications from Mozilla VPN protection
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1 week ago
Troubleshooting speed issues on Mozilla VPN
This article gives you a few troubleshooting tips to fix speed issues on Mozilla VPN.
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How to enable Always-on VPN on Android
Enable “Always-on VPN” on Android to encrypt your connection automatically every time you browse the Internet on your phone.
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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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Why do I see a white screen after updating Mozilla VPN to version 2.8.3?
Some Windows users who have upgraded to Mozilla VPN version 2.8.3 are running into a white screen and are unable to access most of the features when launching the VPN. In this article, you'll find a workaround for this issue.
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RCS messaging and Mozilla VPN
RCS (Rich Communication Services) messaging on iOS 18 does not work when using Mozilla VPN. Learn how to fix or work around this issue.
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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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