Tested with upstream 69.0.2, reproduced. Reported at https://github.com/webcompat/web-bugs/issues/41756 Note that Debian package of Firefox 69.0.1 will produce about 2GB of logs in geckodriver.log, while upstream firefox 69.0.2 will be far more brief. Problem web page: https://www.public.nm.eurocontrol.int/PUBPORTAL/gateway/spec/index.html Loading through selenium / geckodriver / marionette the above website crashes Firefox 69.0.1 (Debian package) and 69.0.2 (tar.bz2 download from mozilla.org) on amd64 architecture. The very same selenium / geckodriver / marionette script in non-headless mode (just comment out the config line for headless) works correctly. The very same selenium / geckodriver / marionette script in headless mode with Firefox ESR 60.9.0esr (Debian package 60.9.0esr-1~deb9u1) (just change the binary_location option to point to it) works correctly. Loading the very same website in Firefox in normal user mode (not scripted through marionette) works fine (all tested versions). Reproduction needs python3-selenium firefoxdriver Debian packages and geckodriver from https://github.com/mozilla/geckodriver/releases (my understanding is that source code for these downloads is in the mozilla tree, building instructions at https://firefox-source-docs.mozilla.org/testing/geckodriver/Building.html the binary download page link to the exact revision of the tree they are built from)
Trying again with the loglevel set to TRACE, I _do_ get the 2GB geckodriver.log file from upstream 69.0.2. I attach an abridged version.