ArgumentError: directory for pid=/.../ not writable

I’ve got the same permission problem where isn’t writable. I wanted to get you some more info by seeing if it reproduces with the official install guide, but that doesn’t fit my system. First it complained because ports 80/443 are already in use, and then it did some e-mail checks that failed. Do you have an app.yml that just makes a docker image that doesn’t require anything external? Presumably this same issue should reproduce with that just as well.