Hi all,

I've faced with the next issue and need some help.
When I send a large request with json content (the request size is above 10kB), Nginx returns "500 Internal Server Error".
But, when I send the same request with less size, it works fine.

My steps:

1. I enabled "debug" logging for error.log, but I don't see any errors.

2. Also, I added '$upstream_response_length $upstream_response_time $upstream_status $request_body'
parameters for logging for access.log.
Once "500 Internal Server Error" error happens, I can see these parameters are empty.
This is an example of my log in access.log:
"POST /report/exportreport HTTP/1.1" 500 186 9216 "-" - - - - "PostmanRuntime/7.25.0" "-"
But I can see these parameters for other successful requests.

3. Also, I tried to use 'client_max_body_size' parameters in config file, but it doesn't work for me.

It seems that Nginx trims large request.
Please, could any help me?

Thank you in advance.

Version of Nginx: 1.14.1

Config Nginx:

user centos;
worker_processes auto;
error_log /var/log/nginx/error.log debug;
pid /run/nginx.pid;

# Load dynamic modules. See /usr/share/doc/nginx/README.dynamic.
include /usr/share/nginx/modules/*.conf;

events {
worker_connections 1024;
}

http {
log_format main '$remote_addr - $remote_user [$time_local] "$request" '
'$status $body_bytes_sent $request_length "$http_referer" '
'$upstream_response_length $upstream_response_time $upstream_status '
'$request_body '
'"$http_user_agent" "$http_x_forwarded_for"';

access_log /var/log/nginx/access.log main;

access_log on;
error_log on;

client_max_body_size 1m;
sendfile on;
tcp_nopush on;
tcp_nodelay on;
keepalive_timeout 65;
types_hash_max_size 2048;

# don't send the nginx version number in error pages and Server header
server_tokens 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;

# enable session resumption to improve https performance
# http://vincent.bernat.im/en/blog/2011-ssl-session-reuse-rfc5077.html
ssl_session_cache shared:SSL:50m;
ssl_session_timeout 1d;
ssl_session_tickets off;

##
# 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;

# Load modular configuration files from the /etc/nginx/conf.d directory.
# See http://nginx.org/en/docs/ngx_core_module.html#include
# for more information.
include /etc/nginx/conf.d/*.conf;

# frontnend

server {
if ($request_method !~ ^(GET|POST)$ )
{
return 405;
}

server_name www.fcs.navitrack.com.ua fcs.navitrack.com.ua;

listen 443 ssl;
listen [::]:443 ssl;
root /home/centos/navitrack/navitrack-fcs/frontend;
index index.html;

ssl_certificate "/etc/letsencrypt/live/www.fcs.navitrack.com.ua/fullchain.pem";
ssl_certificate_key "/etc/letsencrypt/live/www.fcs.navitrack.com.ua/privkey.pem";
ssl_trusted_certificate "/etc/letsencrypt/live/www.fcs.navitrack.com.ua/fullchain.pem";

client_max_body_size 1m;

# Load configuration files for the default server block.
include /etc/nginx/default.d/*.conf;

location / {
add_header 'X-XSS-Protection' '1; mode=block' always;
add_header 'X-Content-Type-Option' 'nosniff' always;
add_header 'X-Frame-Options' 'SAMEORIGIN' always;
add_header 'Content-Security-Policy' "default-src 'self'; script-src 'self' https://maps.googleapis.com; style-src 'self' 'unsafe-inline' https://fonts.googleapis.com; img-src 'self' https://maps.googleapis.com https://maps.gstatic.com data:; font-src 'self' https://fonts.gstatic.com; connect-src 'self' https://api.fcs.navitrack.com.ua https://maps.googleapis.com";
}

location /login {
alias /home/centos/navitrack/navitrack-fcs/frontend;

add_header 'X-XSS-Protection' '1; mode=block' always;
add_header 'X-Content-Type-Option' 'nosniff' always;
add_header 'X-Frame-Options' 'SAMEORIGIN' always;
add_header 'Content-Security-Policy' "default-src 'self'; script-src 'self' https://maps.googleapis.com; style-src 'self' 'unsafe-inline' https://fonts.googleapis.com; img-src 'self' https://maps.googleapis.com https://maps.gstatic.com data:; font-src 'self' https://fonts.gstatic.com; connect-src 'self' https://api.fcs.navitrack.com.ua https://maps.googleapis.com";
}


error_page 404 /404.html;
location = /40x.html {
}

error_page 500 502 503 504 /50x.html;
location = /50x.html {
}
}

# backend

server {
if ($request_method !~ ^(GET|POST|OPTIONS)$ )
{
return 405;
}

server_name api.fcs.navitrack.com.ua;

listen 443 ssl;
listen [::]:443 ssl;

ssl_certificate "/etc/letsencrypt/live/api.fcs.navitrack.com.ua/fullchain.pem";
ssl_certificate_key "/etc/letsencrypt/live/api.fcs.navitrack.com.ua/privkey.pem";
ssl_trusted_certificate "/etc/letsencrypt/live/api.fcs.navitrack.com.ua/fullchain.pem";

client_max_body_size 1m;

location / {

#add CORS
if ($request_method = 'OPTIONS') {
add_header 'Access-Control-Allow-Origin' 'https://fcs.navitrack.com.ua' always;
add_header 'Access-Control-Allow-Methods' 'GET, POST, OPTIONS' always;
add_header 'Access-Control-Allow-Headers' 'Authorization,DNT,User-Agent,X-Requested-With,If-Modified-Since,Cache-Control,Content-Type,Range' always;
add_header 'Access-Control-Max-Age' 86400 always;
add_header 'Content-Type' 'text/plain; charset=utf-8' always;
add_header 'Content-Length' 0 always;

return 204;
}

if ($request_method = 'GET') {
add_header 'Access-Control-Allow-Origin' 'https://fcs.navitrack.com.ua' always;
add_header 'Access-Control-Allow-Methods' 'GET, POST, OPTIONS' always;
add_header 'Access-Control-Allow-Headers' 'Authorization,DNT,User-Agent,X-Requested-With,If-Modified-Since,Cache-Control,Content-Type,Range' always;
}

if ($request_method = 'POST') {
add_header 'Access-Control-Allow-Origin' 'https://fcs.navitrack.com.ua' always;
add_header 'Access-Control-Allow-Methods' 'GET, POST, OPTIONS' always;
add_header 'Access-Control-Allow-Headers' 'Authorization,DNT,User-Agent,X-Requested-With,If-Modified-Since,Cache-Control,Content-Type,Range' always;
}

proxy_pass http://localhost:18745;
proxy_http_version 1.1;
proxy_set_header Upgrade $http_upgrade;
proxy_set_header Connection keep-alive;
proxy_set_header Host $host;
proxy_cache_bypass $http_upgrade;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
proxy_set_header X-Forwarded-Proto $scheme;
proxy_buffer_size 20k;
proxy_buffers 16 256k;
proxy_busy_buffers_size 512k;
}
}
}