When uploading files with non-ASCII characters I get UnicodeEncodeError:
Exception Type: UnicodeEncodeError at /admin/studio/newsitem/add/ Exception Value: \
akaihola's answer was helpful. For those who run django app with uWSGI managed via upstart script, just add these lines to your /etc/init/yourapp.conf
env LANG="en_US.utf8" env LC_ALL="en_US.UTF-8" env LC_LANG="en_US.UTF-8"
It solved the problem for me.