Performance and connectivity Deal with error messages, crashing applications, connectivity issues, and slow performance. In English Secure connection failed and Firefox did not connect How to troubleshoot time related errors on secure websites Website will not allow Firefox to display the page if another site has embedded it Connection settings in Firefox Captive portal detection Fix "The bookmarks and history system will not be functional" error message Mozilla Crash Reporter TB How to troubleshoot security error codes on secure websites Diagnose Firefox issues using Troubleshoot Mode What do the security warning codes mean? Troubleshoot and diagnose Firefox problems Firefox uses too much memory or CPU resources - How to fix Resist Fingerprinting HTTPS-First upgrades to secure connections Task Manager - see whether tabs or extensions are slowing down Firefox Warning Unresponsive script - What it means and how to fix it Firefox can't load websites but other browsers can Rebuilding the Global Database Troubleshoot Mode Thunderbird How do I report a broken site in Firefox desktop? DNS over HTTPS (DoH) FAQs Firefox hangs or is not responding - How to fix How to let Firefox use the internet on your Windows computer How to reset the default user agent on Firefox Firefox DNS over HTTPS Disable Firefox Sync How to enable Always-on VPN on Android Websites look wrong or appear differently than they should Use the Troubleshooting Information page to help fix Firefox issues Where to go for developer support Unload inactive tabs to save system memory in Firefox How can I tell if Mozilla VPN is connected? "Firefox is already running but is not responding" error - How to fix Mozilla VPN won’t connect or keeps disconnecting - How to fix Firefox blocked by macOS 15 Sequoia firewall - What you need to know How to fix the Update Failed error message when updating Firefox Server Not Found - Troubleshoot connection problems Certificate contains the same serial number as another certificate Quick fixes if your Firefox slows down Connecting to unsecured networks while using Mozilla VPN Certificate warnings in Firefox for iOS What is the Mozilla VPN kill switch? Report Site Issues on Firefox for iOS Firefox does not work - Common fixes to get you back up and running 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 Joining public WiFi while on Mozilla VPN How can I help submit and resolve bugs in the MDN content repo? Retrieve a Pocket crash log on Android Thunderbird makes unrequested connections Some videos won't play in background How to obtain the Mozilla VPN Logs 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 Identify problems caused by third-party modules in Firefox for Windows Difficulties opening or using a website in Firefox Focus for Android 100 Why do I see a white screen after updating Mozilla VPN to version 2.8.3? How to find the Pocket app crash logs on iOS RCS messaging and Mozilla VPN 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 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 Crash reports in Firefox for Android 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 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? Where can I get help with the MDN API and documentation? Firefox hangs when copying with Suggested Actions enabled on Windows 11 - What to do How do I report an issue with Firefox Relay? X-Mouse Button Control in Firefox 110 Address screen sharing issues with Firefox on macOS 15 Sequoia Crash reports in Firefox for iOS 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