nginx and FastCGI - "Primary script unknown"

Hi,

I've just downloaded the framework from the master branch and after running docker-compose up -d, I got the following error when requesting for http://localhost:

nginx_1  | 2017/06/01 12:25:31 [error] 7#7: *11 FastCGI sent in stderr: "Primary script unknown" while reading response header from upstream, client: 172.18.0.1, server: , request: "GET / HTTP/1.1", upstream: "fastcgi://172.18.0.4:9000", host: "localhost"

nginx returns a 404 status code response with the text "File not found" in the content.

Im using Linux. Any ideas?