Could you paste here your nginx.conf? It seems like 50x error occurred, so nginx is trying to show you html page with 50x error, but could find the html file. Alternatively, check out Wodby on the Projects page, they provide a simple way to deploy Drupal to your droplets (they also use nginx).

Hello there, late answear but this is the configuration:

server {
listen 80;
server_name www.mysite.com;
rewrite ^/(.*) https://www.mysite.com/$1 permanent;
}

server {

listen 443 ssl;

root /var/www/html/drupal;
index index.php index.html index.htm;

servername www.mysite.com;
sslcertificate /xxxxxxxx
sslcertificatekey /xxxxxxx

errorpage 404 = /index.html;
errorpage 500 502 503 504 /50x.html;
location = /50x.html {
root /usr/share/nginx/html;
}

location = /favicon.ico {
lognotfound off;
access_log off;
}

location = /robots.txt {
allow all;
lognotfound off;
access_log off;
}

location ~ ../..php$ {
return 403;
}

location ~ ^/sites/.*/private/ {
return 403;
}

location ~ (^|/). {
return 403;
}

location / {
try_files $uri @rewrite;
}

location @rewrite {
rewrite ^ /index.php;
}

location ~ .php$ {
fastcgisplitpathinfo ^(.+.php)(/.+)$;
include fastcgiparams;
fastcgiparam SCRIPTFILENAME $requestfilename;
fastcgiintercepterrors on;
fastcgipass unix:/var/run/php5-fpm.sock;

}

location ~ ^/sites/.*/files/styles/ {
try_files $uri @rewrite;
}

location ~* .(js|css|png|jpg|jpeg|gif|ico)$ {
expires max;
lognotfound off;
}
}