Nginx Error: "client sent invalid method while reading client request line"

Hi,

I am running into an error with my Nginx config after following a tutorial on deploying Rails w/Nginx, Puma, and Capistrano.

New versions of the app deploy successfully to the server, however, when I request the droplet’s IP address, I get the following error (according to the Ngninx error log):

2019/11/26 02:49:35 [info] 11483#11483: *9 client sent invalid method while reading client request line, client: xx.xxx.xxx.xxx, server: _, request: "??"

How do I go about debugging this error?

Below is my Nginx config:

upstream puma {
  server unix:///home/deploy/apps/modernpricing/shared/tmp/sockets/modernpricing-puma.sock;
}

server {
  listen 80 default_server;
  listen 443 default_server;
  server_name _;
  ignore_invalid_headers on;

  root /home/deploy/apps/modernpricing/current/public;
  access_log /home/deploy/apps/modernpricing/current/log/nginx.access.log;
  error_log /home/deploy/apps/modernpricing/current/log/nginx.error.log info;

  location ^~ /assets/ {
    gzip_static on;
    expires max;
    add_header Cache-Control public;
  }

  try_files $uri/index.html $uri puma;
  location puma {
    proxy_redirect off;

    proxy_pass http://puma;
  }

  error_page 500 502 503 504 /500.html;
  client_max_body_size 10M;
  keepalive_timeout 10;
}

And here’s the /etc/nginx/nginx.conf file

user www-data;
worker_processes auto;
pid /run/nginx.pid;
include /etc/nginx/modules-enabled/*.conf;

events {
	worker_connections 768;
	# multi_accept on;
}

http {

	##
	# Basic Settings
	##

	sendfile on;
	tcp_nopush on;
	tcp_nodelay on;
	keepalive_timeout 65;
	types_hash_max_size 2048;
	# server_tokens off;

	# server_names_hash_bucket_size 64;
	# server_name_in_redirect off;

	include /etc/nginx/mime.types;
	default_type application/octet-stream;

	##
	# SSL Settings
	##

	ssl_protocols TLSv1 TLSv1.1 TLSv1.2; # Dropping SSLv3, ref: POODLE
	ssl_prefer_server_ciphers on;

	##
	# Logging Settings
	##

	access_log /var/log/nginx/access.log;
	error_log /var/log/nginx/error.log;

	##
	# Gzip Settings
	##

	gzip on;

	# gzip_vary on;
	# gzip_proxied any;
	# gzip_comp_level 6;
	# gzip_buffers 16 8k;
	# gzip_http_version 1.1;
	# gzip_types text/plain text/css application/json application/javascript text/xml application/xml application/xml+rss text/javascript;

	##
	# Virtual Host Configs
	##

	include /etc/nginx/conf.d/*.conf;
	include /etc/nginx/sites-enabled/*;
}