File upload error. Could not move uploaded file.

It does not work at all.

That seems a tad inaccurate, I think what you meant to say was "I have a problem, something I expect to work does not.". Not working at all implies the whole module does nothing at all.

There are in fact automated tests in place that specifically test non-latin characters, however they are Russian characters rather than Chinese, but I can confirm that the functionality does in fact work.

Of course, to ensure that the Automated tests aren't providing false positives I was certain to do a manual test with a file named exactly as you provided (中国.pdf) and everything worked exactly as expected. See screenshot for proof.

However, I don't doubt you are experiencing some issue, which I would be more than happy to look into for you to ensure there is not an issue in certain environments.

Please provide some reproduction steps using http://simplytest.me (so that I can see the issue in the same environment), and failing that, provide me some steps and information about your development environment to ensure I can reproduce the issue.

Again, if you can provide steps on reproducing the issue I would like to try to see if there's anything I can do to help.