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 *https://aka.ms/vs/17/release/vc_redist.x64.exe *https://aka.ms/vs/17/release/vc_redist.x86.exe You may also have to install the Visual Studio 2013 Redistributable Package. You need to reboot the computer. 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