Let's Encrypt doesn't have a tutorial. What instructions did you follow?
But you did configure one. A VirtualHost with ssl engine on and certificate files is that.
Please take this in the friendly suggestion it is meant as ... are you sure you want to be admin for your own server? There is a large learning curve to all the technical details. The certificates are only one thing. If you just want a website or a blog or something there are services you can buy to handle all the tech for you. You then just focus on the content.
It's just a server for personal use, with CasaOS and some applications.
I don't have habilities to admin anything, but it's still nice to learn.
If SSL doesn't work, I'll do without SSL
I was wrong, I followed Certbot tutorials, from let's encrypt website.
Certbot can install certs, but it doesn't have the feature to uninstall them unfortunately. So using an installer without any knowledge of any webserver configuration and then somehow messing up Certbot and/or the contents of /etc/letsencrypt/ can leave people with a pickle.
I didn't know the expression, as I'm french, but I can pretty much see the idea...
Well, if I'm not able to install a ssl certificate without know why, it will be a little bit compromised...
It works without SSL but would probably be better with.
Ah, I see, and Censys also shows staging certs, right? Maybe someone manually copy/pasted some stuff
I'm not a native English speaker too, so I'm preeeetty sure I messed that expression up big time (I now think it's something with "being in a pickle )
First step is to get your webserver back in working order.
Someone or something configured HTTPS virtualhosts in Apache, pointing to files that don't exist (any more). So you need to remove those virtualhosts and make sure you have a working webserver on HTTP.
All right, but like I said, I'm beginner, so except "google, please telle me how remove those virtualhosts and make sure you have a working webserver on HTTP", I don't know what else to do.
This is not a generic support forum, but specifically for Let's Encrypt and only related to certificates/TLS more in general. Not all kinds of generic computer issues, sorry. Maybe you can find support somewhere on the "casaOS" support channels.