Defaulting New Projects to Python 3

New projects that are just getting started with Read the Docs will now use Python 3 by default. While it is still possible to configure your project to use Python 2.7 with our configuration file, we think it’s important to help push the Python ecosystem towards adopting Python 3.

Our default Python version is currently Python 3.7. Projects can also select Python versions 3.6 and 3.5 using our default build image. We will eventually remove support for building projects with Python versions 3.3 and 3.4, however it is still possible to select a build image with support for either version.

To select a specific version of Python, other than our default, you can use our configuration file to specify a Python version, using the python.version configuration option.

If your project does require Python version 3.3 or 3.4, you can only select these versions if you also specify stable build image for your project’s build.image (legacy) configuration option. As we release new versions of our build image, this stable image will eventually lose support for Python 3.3 and 3.4, so it’s suggested that your project upgrade to a supported version of Python.