Your System Details show Firefox 107.0 on Windows Vista. Are you running Firefox in compatibility mode as XP and Vista haven't been supported for quite some time (current minimum is Windows 7) ? *https://www.mozilla.org/en-US/firefox/110.0/system-requirements/ ---- An error message about XPCOM missing or about platform version usually happens because of a failed Firefox update that left you with a mixture of old and updated files in the Firefox program folder. This can happen in case security software was keeping a handle of some of the files in the Firefox program folder preventing Firefox from replacing all the files. You need to do a clean reinstall and remove the Firefox program folder to ensure that all files are replaced. You may have to disable security software temporarily in case the problem persists.