NginX http redirection to https returns unreadable respone - http

Question

I want to redirect all http requests to https with NginX, but I have some difficulties with it.
Here is my vhost file :
server {
gzip off;
listen 80;
listen [::]:80;
server_name mydomain.fr www.mydomain.fr sub.otherdom.fr otherdom.fr;
return 301 https://$host$request_uri;
}
server {
listen 443 ssl http2;
listen [::]:443 ssl http2;
root /usr/share/nginx/html;
index index.html index.htm;
ssl on;
server_name mydomain.fr www.mydomain.fr sub.otherdom.fr otherdom.fr;
ssl_certificate /root/tmp/live-ecdsa/mydomain.fr/0001_chain.pem;
ssl_certificate_key /root/tmp/live-ecdsa/mydomain.fr/privkey-p384.pem;
access_log /var/log/nginx/default.access.log;
charset utf-8;
location / {
try_files $uri $uri/ /index.html;
}
}
Trying to access these domain over plain http with different browsers results in the following :
Chrome/Firefox : downloading a file filled with bytes data
Edge : displays a blank page with €ÿÿÿÿ
A curl -I mydomain.fr outputs ▒▒
Accessing these domains directly over https works.
I have already tried with both return 301 https://$host$request_uri; and return 301 https://$server_name$request_uri;

Answer 1

I suspect it has something to do with the fairly large number of server names you are declaring in the one server name field inside a pretty locally scoped context. Although, if I'm honest thats a fairly unfounded assertion based on habits I've become user to.
I'd suggest a few things, although generally most of this wont fix your problem, it might make it easier to work out whats happening:
split your config into purposed files. Ie. Create a ssl.conf in another folder which contains all youe cert settings, cipher suites etc. Then add an include /path/to/ssl.conf in your config.
dont use $host, this variable can be set by the use so probably a less than great idea
Assuming you have all the other relevant ssl/tls settings referenced from somewhere else then the below should roughly work.
server {
listen 80 default_server;
listen [::]:80 default_server;
server_name mydomain.fr;
return 301 https://$server_name$request_uri;
}
server {
listen 443 ssl http2 default_server;
listen [::]:443 ssl http2 default_server;
root /usr/share/nginx/html;
$server_name mydomain.fr
location / {
try_files $uri $uri/ /index.html;
}
}

Answer 2

Well, although user6788523 response helped me with the debugging, the fault was on my side.
I had several other vhost files with the http2 directive associated with the http port 80 (listen [::]:80 http2;). Removing the http2 directive resolved the problem.
This setting must be used only with ssl enabled server block