Tor Browser v12.0.4 not working, older system

For legacy reasons, I’m running Ubuntu 14.04 and cannot upgrade to a newer distro.

Last night I attempted to launch Tor Browser, it wanted to update and then: nothing. What is this XPCOM thing and why isn’t there a fallback, for legacy and other users who for one reason or another, cannot update to newer (or the newest) Linux distro?

Isn’t this project supposed to support users in third world and sketchy locations, where suboptimal hardware and software cannot be avoided, instead of shafting them by breaking backwards compatibility?

$ ./start-tor-browser.desktop --verbose
Launching ‘./Browser/start-tor-browser --detach --verbose’…
XPCOMGlueLoad error for file /home/intern/Downloads/browsers/tor/tor-browser/Browser/
/home/intern/Downloads/browsers/tor/tor-browser/Browser/ undefined symbol: gdk_window_show_window_menu
Couldn’t load XPCOM.