Sphinx-quickstart doesn't work

An alternative way to invoke sphinx-quickstart is to explicitly load Sphinx's quickstart module. For Sphinx v1.7+:

python -m sphinx.cmd.quickstart

For older versions of Sphinx:

python -m sphinx.quickstart

For example:

$ /c/Python35/python -m sphinx.quickstart
Welcome to the Sphinx 1.6.2 quickstart utility.
...