i have problems with HTTP2 protocol on my NGINX server, this is my configuration

```
listen 443 ssl http2;
server_name adomain.com;
root /var/www/project;

limit_req   zone=one  burst=60 nodelay;

add_header Strict-Transport-Security "max-age=2592000; includeSubdomains;" always;
ssl_certificate     /etc/letsencrypt/live/fullchain.pem;
ssl_certificate_key /etc/letsencrypt/live/privkey.pem;
ssl_protocols   TLSv1 TLSv1.1 TLSv1.2;
ssl_ciphers "EECDH+AESGCM:EDH+AESGCM:ECDHE-RSA-AES128-GCM-SHA256:AES256+EECDH:DHE-RSA-AES128-GCM-SHA256:AES256+EDH:ECDHE-RSA-AES256-GCM-SHA384:DHE-RSA-AES256-GCM-SHA384:ECDHE-RSA-AES256-SHA384:ECDHE-RSA-AES128-SHA256:ECDHE-RSA-AES256-SHA:ECDHE-RSA-AES128-SHA:DHE-RSA-AES256-SHA256:DHE-RSA-AES128-SHA256:DHE-RSA-AES256-SHA:DHE-RSA-AES128-SHA:ECDHE-RSA-DES-CBC3-SHA:EDH-RSA-DES-CBC3-SHA:AES256-GCM-SHA384:AES128-GCM-SHA256:AES256-SHA256:AES128-SHA256:AES256-SHA:AES128-SHA:DES-CBC3-SHA:HIGH:!aNULL:!eNULL:!EXPORT:!DES:!MD5:!PSK:!RC4";
ssl_prefer_server_ciphers on;
ssl_session_cache   shared:SSL:10m;
ssl_session_timeout 10m;
ssl_dhparam /etc/nginx/ssl/dhparam.pem;

resolver 8.8.8.8;
ssl_stapling on;
ssl_stapling_verify on;

keepalive_timeout   70;

```

I can’t see the error on my iOS device (safari 11), it's very strange the webpage is a SPA ( angular ) that app makes requests to an API, the apps loads over HTTP2 but when the app has to make requests to the API it fails, disabling HTTP2 from the `listen` makes everything works as espected

The ciphers for both servers frontend/backend are the same

In Chrome/Firefox/IE works fine, i don't know what is wrong with Safari or my server config

The error.log and adomain-error.log are empty when Safari fails

Nginx Version

```
nginx version: nginx/1.12.2
built by gcc 4.8.5 20150623 (Red Hat 4.8.5-16) (GCC) 
built with OpenSSL 1.0.2k-fips  26 Jan 2017
TLS SNI support enabled
configure arguments: --prefix=/etc/nginx --sbin-path=/usr/sbin/nginx --modules-path=/usr/lib64/nginx/modules --conf-path=/etc/nginx/nginx.conf --error-log-path=/var/log/nginx/error.log --http-log-path=/var/log/nginx/access.log --pid-path=/var/run/nginx.pid --lock-path=/var/run/nginx.lock --http-client-body-temp-path=/var/cache/nginx/client_temp --http-proxy-temp-path=/var/cache/nginx/proxy_temp --http-fastcgi-temp-path=/var/cache/nginx/fastcgi_temp --http-uwsgi-temp-path=/var/cache/nginx/uwsgi_temp --http-scgi-temp-path=/var/cache/nginx/scgi_temp --user=nginx --group=nginx --with-compat --with-file-aio --with-threads --with-http_addition_module --with-http_auth_request_module --with-http_dav_module --with-http_flv_module --with-http_gunzip_module --with-http_gzip_static_module --with-http_mp4_module --with-http_random_index_module --with-http_realip_module --with-http_secure_link_module --with-http_slice_module --with-http_ssl_module --with-http_stub_status_module --with-http_sub_module --with-http_v2_module --with-mail --with-mail_ssl_module --with-stream --with-stream_realip_module --with-stream_ssl_module --with-stream_ssl_preread_module --with-cc-opt='-O2 -g -pipe -Wall -Wp,-D_FORTIFY_SOURCE=2 -fexceptions -fstack-protector-strong --param=ssp-buffer-size=4 -grecord-gcc-switches -m64 -mtune=generic -fPIC' --with-ld-opt='-Wl,-z,relro -Wl,-z,now -pie'

```

---

**UPDATE**

The console on my IPhone says `Protocol error` so i'm pretty sure that it's an error of the IOS 11

**UPDATE 2**

I have found this post

```
https://www.nginx.com/blog/http2-theory-and-practice-in-nginx-stable-13/

```

It explains that if you support TLSv < 1.2 you will end up in a `PROTOCOL ERROR` , leaving in my server config just TLSv1.2 makes the app works again, but it's buggy , some requests will fail ... that's beyond my comprehension, once again in Chrome/Firefox it's working but in my mobile safari it doesn't

**UPDATE 3** [2019/02/28]

There was a bug on our NGINX config for the OPTIONS Method of a CORS request causing duplicated **Content-Length** and **Content-Type** headers to be responded, after we solve that the app started working fine in HTTP/2, we also changed the status of the OPTIONS response from 200 to 204