I hit the same bug when running a Python/Django site with mod_wsgi. Django tried to os.stat() a unicode filepath with u'\xc4' in it and failed. That's indeed what Python does when run with LANG=C. My fix was to add ENV="env -i LANG=en_US.UTF-8 PATH=/usr/local/bin:/usr/bin:/bin" in /etc/default/apache2, but /etc/apache2/envvars sounds more appropriate.