First reported at https://bugzilla.redhat.com/show_bug.cgi?id=1204428 Try: /usr/bin/Thunar "`printf '\374'`" result: core dumped. BTW, I have LANG=en_US; yet, if I run Thunar with an UTF8-encoded umlaut, it displays the dialog box actually showing that umlaut, which it shouldn't (it should display gibberish instead), since the command line is latin1 encoded with LANG=en_US.
Thunar 1.8.2 doesn't crash anymore, no matter if LANG=en_US.UTF-8 or en_US is used. When no file or folder exists with that name, thunar just displays a dialog telling "Failed to open "�": Error when getting information for file “/home/andre/projects/xfce/thunar/�”: No such file or directory". When a file exists with that name, the default application opens it. When a folder exists with that name, thunar opens it and the title is � (invalid encoding) - File Manager. Probably it got fixed while porting to gtk3 or with newer versions of glib, please reopen if you are still able to crash Thunar.