Performance and connectivity Deal with error messages, crashing applications, connectivity issues, and slow performance. In English Secure connection and security warning error pages in Firefox Server Not Found - Troubleshoot connection problems Troubleshoot time-related errors on secure websites Fix "The bookmarks and history system will not be functional" error message Fix error “Website will not allow Firefox to display the page.” Use Troubleshoot Mode in Firefox Captive portal detection Connection settings in Firefox Troubleshoot security error codes on secure websites Troubleshoot and diagnose Firefox problems Crash reports in Firefox for Android Firefox can't load websites but other browsers can Task Manager - see whether tabs or extensions are slowing down Firefox Fix Firefox using too much memory or CPU resources Troubleshoot Mode Thunderbird How can I tell if Mozilla VPN is connected? Resist Fingerprinting Firefox hangs or is not responding - How to fix How Thunderbird for Android avoids leaking your IP address to SMTP servers Warning Unresponsive script - What it means and how to fix it Firefox DNS over HTTPS How do I report a broken site in Firefox desktop? Websites look wrong or appear differently than they should How to fix the Update Failed error message when updating Firefox Disable Firefox Sync Joining public WiFi while on Mozilla VPN How to let Firefox use the internet on your Windows computer Use the Troubleshooting Information page to help fix Firefox issues What do the security warning codes mean? Where to go for developer support Troubleshoot Mozilla VPN connection problems Unload inactive tabs to save system memory in Firefox How to enable Always-on VPN on Android Mozilla Crash Reporter TB Rebuilding the Global Database How to reset the default user agent on Firefox DNS over HTTPS (DoH) FAQs Firefox says it's just updated every time it starts - how to fix What is the Mozilla VPN kill switch? Crash reports in Firefox for iOS Certificate contains the same serial number as another certificate Firefox does not work - Common fixes to get you back up and running Quick fixes if your Firefox slows down "Firefox is already running but is not responding" error - How to fix Thunderbird makes unrequested connections Rate your Firefox experience, surveys and out of date messages (Heartbeat) Drag and Drop errors with Firefox Launcher Process enabled and Windows UAC disabled - How to Fix Profiling Thunderbird Performance Report a broken website in Firefox for iOS Connecting to unsecured networks while using Mozilla VPN Troubleshooting speed issues on Mozilla VPN How do I contact MDN Plus support? How can I help submit and resolve bugs in the MDN content repo? Firefox hangs when copying with Suggested Actions enabled on Windows 11 - What to do How do I report an issue with Firefox Relay? Firefox blocked by macOS 15 Sequoia firewall - What you need to know Unsent crash reports in Firefox Unsent crash reports in Firefox for Android Firefox takes a long time to start up Firefox uses too many CPU resources - How to fix Websites say that Firefox is outdated or incompatible even though it's the latest version Memory constraints, Firefox performance and Firewalls Rebuilding Global Database How to resolve weak crypto error messages on Firefox Certificate warnings in Firefox for iOS Some videos won't play in background 64-bit Firefox crashes with Citrix's XenApp VM How to obtain the Mozilla VPN Logs Firefox for iOS won't load web pages How to fix an error when trying to open Telegram or Slack on Firefox Compacting folders - Potential complications Solutions for "Can not create temp folder archive" error when installing Firefox (Windows 10) Fritz!box isn't working when Mozilla VPN is on Identify problems caused by third-party modules in Firefox for Windows The language of the websites I visit changes when I turn Mozilla VPN on - What to do Difficulties opening or using a website in Firefox 100 Difficulties opening or using a website in Firefox Focus for Android 100 Where can I get help with the MDN API and documentation? Why do I see a white screen after updating Mozilla VPN to version 2.8.3? X-Mouse Button Control in Firefox 110 RCS messaging and Mozilla VPN Address screen sharing issues with Firefox on macOS 15 Sequoia HTTPS-First upgrades to secure connections Troubleshoot Firefox crashes (closing or quitting unexpectedly) Firefox is stuck in Troubleshoot Mode Firefox repeatedly opens empty tabs or windows after you click on a link Fix video and audio problems on Firefox for Windows N editions Avoid crashes - Tips and tricks Problems with email and how to find help Firefox keeps crashing at startup Home page with pipe character opens extra tabs when Firefox starts How to run Firefox when your profile is missing or inaccessible