FastCGI sent in stderr: "Primary script unknown" while reading response header from upstream nginx error

Question

I user nginx docker as proxy server, and there are other containers running: nuxt.js and php-fpm.

This is my fpm's conf file:

server {
  server_name fpm.me.com;
  root /var/www/fpm/html;

  location / {
    # try to serve file directly, fallback to index.php
    try_files $uri /index.php$is_args$args;
  }

  #location ~ ^/index\.php(/|$) {
  # https://stackoverflow.com/questions/68350978/nginx-serving-only-but-not-any-other-files
  location ~ \.php(/|$) {
    fastcgi_pass fpm:9000;
    fastcgi_split_path_info ^(.+\.php)(/.*)$;
    include fastcgi_params;
    fastcgi_param SCRIPT_FILENAME $realpath_root$fastcgi_script_name;
    fastcgi_param DOCUMENT_ROOT $realpath_root;
    #internal;
  }

  location ~ \.php$ {
    return 404;
  }
  access_log off;
  error_log /dev/stderr;
}

But when I type fpm.me.com, I get this error in nginx's log file:

2021/08/03 09:31:18 [error] 31#31: *13 FastCGI sent in stderr: "Primary script unknown" while reading response header from upstream, client: MY_IP, server: fpm.me.com, request: "GET / HTTP/1.1", upstream: "fastcgi://172.20.0.8:9000", host: "fpm.me.com"

I saw other answers in StackOverFlow, ServerFault and other websites but it seems it did not help me.

Answer 1

This doesn't look valid:

fastcgi_pass fpm:9000

You have 2 options:

• use a unix socket:

  fastcgi_pass unix:/run/php/php7.4-fpm.sock;

• use TCP port

  fastcgi_pass 127.0.0.1:9000;

Option 1 is slightly faster and doesn't have the risk of ports exhaustion if you receive many concurrent connections.

Answer 2

The issue was with the volumes I mounted for nginx and fpm which were not the same.

This is my compose file:

services:
  nginx:
    image: nginx
    volumes:
      - './fpm/:/var/www/fpm/'
  fpm:
    image: custom
    volumes:
      - './fpm/:/var/www/'

While it should have been like this to work:

services:
  nginx:
    image: nginx
    volumes:
      - './fpm/:/var/www/fpm/'
  fpm:
    image: custom
    volumes:
      - './fpm/:/var/www/fpm/'