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