You can check for issues caused by a corrupted or incomplete Visual C++ installation that is missing runtime components (Redistributable Packages) required by Firefox, especially VCRUNTIME140_1.dll. See "Visual Studio 2015, 2017, 2019, and 2022": *https://docs.microsoft.com/en-US/cpp/windows/latest-supported-vc-redist Download the latest vc_redist.x64 and vc_redist.x86 files. *https://aka.ms/vs/17/release/vc_redist.x64.exe *https://aka.ms/vs/17/release/vc_redist.x86.exe You need to reboot the computer. <hr> *https://support.mozilla.org/en-US/kb/troubleshoot-and-diagnose-firefox-problems Try to start Firefox in <b>Troubleshoot Mode</b> to see if that works. *Windows: hold down the Shift key while starting Firefox *Mac: hold down the Options key while starting Firefox *https://support.mozilla.org/en-US/kb/diagnose-firefox-issues-using-troubleshoot-mode ---- You can check the connection settings and check for possible issues with a Proxy or VPN service. *Settings -> General -> Network: Connection -> Settings If you do not need to use a Proxy to connect to internet, select "No Proxy" if "Use the system proxy settings" or one of the others do not work properly. See also: *https://support.mozilla.org/en-US/kb/connection-settings-firefox *https://support.mozilla.org/en-US/kb/websites-dont-load-troubleshoot-and-fix-errors