When uploading files with non-ASCII characters I get UnicodeEncodeError:
Exception Type: UnicodeEncodeError at /admin/studio/newsitem/add/
Exception Value: \
As said before, it is related to locale. For exemple, if you use gunicorn to serve your django application, you may have an init.d script (or, as me, a runit script), where you can set the locale.
To solve UnicodeEncodeError with file upload, put something like export LC_ALL=en_US.UTF8 in your script that run your app.
For example, this is mine (using gunicorn and runit):
#!/bin/bash
export LC_ALL=en_US.UTF8
cd /path/to/app/projectname
exec gunicorn_django -b localhost:8000 --workers=2
Also, you can check your locale in your template, using this in your view:
import locale
data_to_tpl = {'loc': locale.getlocale(), 'lod_def': locale.getdefaultlocale()}
And just disply {{loc}} - {{loc_def}} in your template.
You will have more information about your locale settings! That was very usefull for me.