it’s just a simple question, but I haven’t found an - explicit - answer for it, so I hope you can clariffy it for me.
I created a cert with certbot for an expressjs-Webserver. For this, I run a HTTP-only server once for the certbot to find the acme-challenge-file.
Now, as the server is running with ssl as wished, the acme-challenge-file for the renewal can be found ONLY over HTTPS (but with the same path). Will this be a problem later?
Yes, Let's Encrypt will follow redirects, even to HTTPS.
This means the normal, HTTP-based method of confirming your ownership of the domain. Let's Encrypt also supports other validation methods like a DNS-based one.