Firefox Portable is a 3rd-party build. Support is available here: http://portableapps.com/forums/support/firefox_portable

''<p>hilrie [[#question-1299214|said]]</p>'' <blockquote>I removed gtk3 from my distro and Firefox portable would still run/work.... However The Tor browser which is also portable does not run without gtk3 and it is based on Firefox ... what is going on here ? </blockquote> What portable Firefox are you referring to as by portable Firefox normally people refer to https://portableapps.com/apps/internet/firefox_portable which is only for Windows. Firefox for Linux from mozilla.org since [https://www.mozilla.org/firefox/46.0/releasenotes/ 46.0] (released on April 26, 2016) has required GTK 3.4 (three.four) at minimum to run though most pretty recent distros in last several years now (that is not Long Term Support or LTS) have much more current GTK3 versions. Some Linux distros may have delayed this change from GTK 2.18 to 3.4 (three.four) or newer minimum for a while at the time in their own packaged builds of Firefox. However Firefox for Linux as of [https://www.mozilla.org/firefox/78.0/releasenotes/ 78.0] and later now require GTK+ 3.14 (three.fourteen) or newer. https://www.mozilla.org/firefox/79.0/system-requirements/