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

Posted November 26, 2019 9.6k views
Ruby on RailsNginx


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:, 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/;
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/*;

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2 answers

Hey @KDSys, thanks for offering your help here. I appreciate it.

It looks like my issue was rails-specific as I was able to get past this error by changing force_ssl = true to force_ssl = false in my config/environments/production.rb file.

Of course, the other option is to enable SSL for nginx and the app. That’s up next :)

edited by AHA

Hi @jmarbch,

I have a few suggestions to help you resolve the issue. First one is quite the long shot however you didn’t specify a server_name in your server block.

Additionally, if you try with a blank index.html file is the same error returned? I’m asking as I’ve seen this issue before and it was actually being caused by the application rather than a problem on the server level.