Performance and connectivity Deal with error messages, crashing applications, connectivity issues, and slow performance. Na Angele Server Not Found - Troubleshoot connection problems Secure connection and security warning error pages in Firefox 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 Use Troubleshoot Mode in Firefox Troubleshoot security error codes on secure websites Fix error “Website will not allow Firefox to display the page.” Crash reports in Firefox for Android Troubleshoot Mode Thunderbird Troubleshoot and diagnose Firefox problems Warning Unresponsive script - What it means and how to fix it Firefox can't load websites but other browsers can Firefox DNS over HTTPS How can I tell if Mozilla VPN is connected? Fix Firefox using too much memory or CPU resources Use the Troubleshooting Information page to help fix Firefox issues Firefox hangs or is not responding - How to fix Task Manager - see whether tabs or extensions are slowing down Firefox Resist Fingerprinting How to reset the default user agent on Firefox What do the security warning codes mean? How to fix the Update Failed error message when updating Firefox Where to go for developer support Rebuilding the Global Database Disable Firefox Sync Unload inactive tabs to save system memory in Firefox How Thunderbird for Android avoids leaking your IP address to SMTP servers Unsent crash reports in Firefox How to let Firefox use the internet on your Windows computer "Firefox is already running but is not responding" error - How to fix What is the Mozilla VPN kill switch? Websites look wrong or appear differently than they should How do I report a broken site in Firefox desktop? Joining public WiFi while on Mozilla VPN Certificate contains the same serial number as another certificate How to obtain the Mozilla VPN Logs Connecting to unsecured networks while using Mozilla VPN Troubleshooting speed issues on Mozilla VPN How to enable Always-on VPN on Android Troubleshoot Mozilla VPN connection problems X-Mouse Button Control in Firefox 110 Crash reports in Firefox for iOS Quick fixes if your Firefox slows down Thunderbird makes unrequested connections Certificate warnings in Firefox for iOS Some videos won't play in background 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 DNS over HTTPS (DoH) FAQs Report a broken website in Firefox for iOS Identify problems caused by third-party modules in Firefox for Windows HTTPS-First upgrades to secure connections 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 Memory constraints, Firefox performance and Firewalls Mozilla Crash Reporter TB Rebuilding Global Database How to resolve weak crypto error messages on Firefox Profiling Thunderbird Performance 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 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? Firefox hangs when copying with Suggested Actions enabled on Windows 11 - What to do How do I report an issue with Firefox Relay? 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 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