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"Firefox is already running but is not responding" error - How to fix Rate your Firefox experience, surveys and out of date messages (Heartbeat) Certificate warnings in Firefox for iOS How to obtain the Mozilla VPN Logs Solutions for "Can not create temp folder archive" error when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