Error 521 after latest update due to CloudFlare settings

I tried this but the setup didn’t start. Grep did work and I copied all data to a safe place so I can use it again. But now when I try to run the setup again it says

This will show you what command is using port 80
COMMAND PID USER FD TYPE DEVICE SIZE/OFF NODE NAME
docker-pr 27737 root 4u IPv6 47517368 0t0 TCP *:http (LISTEN)

If you are trying to run Discourse simultaneously with another web
server like Apache or nginx, you will need to bind to a different port

See Run other websites on the same machine as Discourse

If you are reconfiguring an already-configured Discourse, use

./launcher stop app

to stop Discourse before you reconfigure it and try again.

I think the situation is now just getting worse.