This is just a collection of utilities for python-requests, but don't really belong in requests proper. The minimum tested requests version is 2.1.0. In reality, the toolbelt should work with 2.0.1 as well, but some idiosyncracies prevent effective or sane testing on that version.On Python 3.3.0 and 3.3.1, the standard library's http module will fail when passing an instance of the MultipartEncoder. This is fixed in later minor releases of Python 3.3. Please consider upgrading to a later minor version or Python 3.4. There is absolutely nothing this library can do to work around that bug.