EDIT: I have posed this quest over on Linuxquestions.org's forum for it can be as much a Linux question as it can a Firefox question. Let me add, the command name used is "firefox" in the Terminal. Add also my computer is : IBM System X Server (4362), 64-Bit 2-Core Intel, 4 G memory./EDIT Launching Firefox from the command line terminal generates various-numbered errors while otherwise successfully launching normally. It's always a pair of lines containing all the same text except for reference in one to "ref" and the other to "unref." Today I launched Firefox from Terminal twice and saw a different-numbered error, but the same text: First launch: (firefox:6676): GLib-GObject-CRITICAL **: g_object_ref: assertion 'object->ref_count > 0' failed (firefox:6676): GLib-GObject-CRITICAL **: g_object_unref: assertion 'object->ref_count > 0' failed And: (/usr/lib/firefox/firefox:6756): GLib-GObject-CRITICAL **: g_object_ref: assertion 'object->ref_count > 0' failed (/usr/lib/firefox/firefox:6756): GLib-GObject-CRITICAL **: g_object_unref: assertion 'object->ref_count > 0' failed Second launch: (firefox:6944): GLib-GObject-CRITICAL **: g_object_ref: assertion 'object->ref_count > 0' failed (firefox:6944): GLib-GObject-CRITICAL **: g_object_unref: assertion 'object->ref_count > 0' failed and: (/usr/lib/firefox/firefox:7016): GLib-GObject-CRITICAL **: g_object_ref: assertion 'object->ref_count > 0' failed (/usr/lib/firefox/firefox:7016): GLib-GObject-CRITICAL **: g_object_unref: assertion 'object->ref_count > 0' failed Running 64-bit versions of Linux Mint 17.3 and Firefox 59.0.2. Firefox launches a profile dialogue from which I optionally choose an empty profile or go ahead and start the browser using my usual profile. I could skip the profile manager, but it's there if ever I need it for some reason. And I don't have to remember how to access it if I need it. Thank you.