Performance and connectivity Deal with error messages, crashing applications, connectivity issues, and slow performance. Anglų kalba Secure connection and security warning error pages in Firefox Fix error “Website will not allow Firefox to display the page.” Connection settings in Firefox Troubleshoot time-related errors on secure websites Fix "The bookmarks and history system will not be functional" error message Captive portal detection Use Troubleshoot Mode in Firefox Troubleshoot and diagnose Firefox problems Troubleshoot security error codes on secure websites Resist Fingerprinting Warning Unresponsive script - What it means and how to fix it Use the Troubleshooting Information page to help fix Firefox issues Troubleshoot Mode Thunderbird Task Manager - see whether tabs or extensions are slowing down Firefox Unload inactive tabs to save system memory in Firefox Firefox DNS over HTTPS Crash reports in Firefox for Android Firefox can't load websites but other browsers can How Thunderbird for Android avoids leaking your IP address to SMTP servers Rebuilding the Global Database How to enable Always-on VPN on Android Firefox hangs or is not responding - How to fix Quick fixes if your Firefox slows down DNS over HTTPS (DoH) FAQs How can I tell if Mozilla VPN is connected? Fix Firefox using too much memory or CPU resources How to reset the default user agent on Firefox Disable Firefox Sync How to let Firefox use the internet on your Windows computer Websites look wrong or appear differently than they should Firefox takes a long time to start up Server Not Found - Troubleshoot connection problems Thunderbird makes unrequested connections Where to go for developer support Report Site Issues on Firefox for iOS Troubleshoot Mozilla VPN connection problems Crash reports in Firefox for iOS How to fix the Update Failed error message when updating Firefox Rate your Firefox experience, surveys and out of date messages (Heartbeat) What do the security warning codes mean? Some videos won't play in background How do I report a broken site in Firefox desktop? What is the Mozilla VPN kill switch? Connecting to unsecured networks while using Mozilla VPN Compacting folders - Potential complications Identify problems caused by third-party modules in Firefox for Windows How do I report an issue with Firefox Relay? Firefox blocked by macOS 15 Sequoia firewall - What you need to know HTTPS-First upgrades to secure connections "Firefox is already running but is not responding" error - How to fix How can I help by submitting mobile performance data? Mozilla Crash Reporter TB Certificate warnings in Firefox for iOS Joining public WiFi while on Mozilla VPN Difficulties opening or using a website in Firefox Focus for Android 100 How can I help submit and resolve bugs in the MDN content repo? Where can I get help with the MDN API and documentation? 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 Certificate contains the same serial number as another certificate Firefox does not work - Common fixes to get you back up and running Memory constraints, Firefox performance and Firewalls 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 How to obtain the Mozilla VPN Logs 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 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 How do I contact MDN Plus support? 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 Address screen sharing issues with Firefox on macOS 15 Sequoia 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 Firefox keeps crashing at startup Avoid crashes - Tips and tricks Fix video and audio problems on Firefox for Windows N editions Problems with email and how to find help Home page with pipe character opens extra tabs when Firefox starts How to run Firefox when your profile is missing or inaccessible