Performance and connectivity Deal with error messages, crashing applications, connectivity issues, and slow performance. NgesiNgesi Secure connection and security warning error pages in Firefox Troubleshoot time-related errors on secure websites Fix error “Website will not allow Firefox to display the page.” Fix "The bookmarks and history system will not be functional" error message Connection settings in Firefox Troubleshoot security error codes on secure websites Captive portal detection Unload inactive tabs to save system memory in Firefox Resist Fingerprinting Use Troubleshoot Mode in Firefox Firefox can't load websites but other browsers can Firefox DNS over HTTPS Troubleshoot Mode Thunderbird Task Manager - see whether tabs or extensions are slowing down Firefox What do the security warning codes mean? How do I report a broken site in Firefox desktop? Firefox uses too much memory or CPU resources - How to fix Disable Firefox Sync Certificate contains the same serial number as another certificate Where to go for developer support DNS over HTTPS (DoH) FAQs Warning Unresponsive script - What it means and how to fix it Crash reports in Firefox for Android Firefox hangs or is not responding - How to fix Quick fixes if your Firefox slows down Rebuilding the Global Database How to enable Always-on VPN on Android How do I contact MDN Plus support? Troubleshoot Mozilla VPN connection problems How can I tell if Mozilla VPN is connected? Use the Troubleshooting Information page to help fix Firefox issues Crash reports in Firefox for iOS How Thunderbird for Android avoids leaking your IP address to SMTP servers Websites look wrong or appear differently than they should Certificate warnings in Firefox for iOS HTTPS-First upgrades to secure connections How to fix the Update Failed error message when updating Firefox How to let Firefox use the internet on your Windows computer Troubleshoot and diagnose Firefox problems "Firefox is already running but is not responding" error - How to fix Mozilla Crash Reporter TB Thunderbird makes unrequested connections How to reset the default user agent on Firefox Compacting folders - Potential complications Server Not Found - Troubleshoot connection problems 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 What is the Mozilla VPN kill switch? Connecting to unsecured networks while using Mozilla VPN Firefox for iOS won't load web pages Identify problems caused by third-party modules in Firefox for Windows How can I help submit and resolve bugs in the MDN content repo? How do I report an issue with Firefox Relay? 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 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 Rebuilding Global Database Rate your Firefox experience, surveys and out of date messages (Heartbeat) How to resolve weak crypto error messages on Firefox Some videos won't play in background How to obtain the Mozilla VPN Logs Profiling Thunderbird Performance Report Site Issues on Firefox for iOS Joining public WiFi while on Mozilla VPN How to fix an error when trying to open Telegram or Slack on Firefox Solutions for "Can not create temp folder archive" error when installing Firefox (Windows 10) 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 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? 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 Address screen sharing issues with Firefox on macOS 15 Sequoia 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 Avoid crashes - Tips and tricks Problems with email and how to find help Firefox keeps crashing at startup Fix video and audio problems on Firefox for Windows N editions Home page with pipe character opens extra tabs when Firefox starts How to run Firefox when your profile is missing or inaccessible