How to Solve 502 Bad Gateway error in Nginx Magento 2?

Question

I am getting the error code 502 Bad Gateway in my Magento Installation with the following error in error log

*1 upstream sent too big header while reading response header from upstream, client: 127.0.0.1, server: v3.com, request: "GET /new-arrivals/ HTTP/1.1", upstream: "fastcgi://unix:/run/php/php7.1-fpm.sock:", host: "v3.com"

How to solve this?

Answer 1

I installed the magento2 when I am trying to open some pages facing 502 nginx issue,

in nginx logs it is showing

upstream sent too big header while reading response header from upstream,

then solved this issue by modifying this file

/etc/nginx/nginx.conf

add this line of codes inside http{}

fastcgi_buffers 16 16k;
fastcgi_buffer_size 32k;
proxy_buffer_size 128k;
proxy_buffers 4 256k;
proxy_busy_buffers_size 256k;

for more details refer below link

https://bobcares.com/blog/magento-502-bad-gateway/?unapproved=75360&moderation-hash=21aca5cefbcdd86f62c492697cb64954#comment-75360

Answer 2

Are you using NGINX? It seems there is misconfiguration with your server. Try to add:

http {
  .... your config ...

  fastcgi_buffers 16 16k;
  fastcgi_buffer_size 32k;
}

Restart NGINX and after, the error related to the header size should be solved. Source: https://stackoverflow.com/questions/23844761/upstream-sent-too-big-header-while-reading-response-header-from-upstream

Answer 3

I got same type issue for 502 Bad Gateway error in Nginx Magento 2

sudo cat /var/log/nginx/error.log

Content as Below:

FastCGI sent in stderr: "PHP message: PHP Fatal error: Uncaught ReflectionException: Class Magento\Framework\App\ResourceConnection\Proxy does not exist in ClassReader.php:26

magento 2 checkout upstream sent too big header while reading response header from upstream, client: server: d request: "POST /customer/account/loginPost/referer/aHR0cDovL2Rldi5lb25iYXphci5jb20vY2hlY2tvdXQv/ HTTP/1.1", upstream: "fastcgi://unix:/run/php/php7.x-fpm.sock:", host: "dev.eonbazar.com", referrer: " /checkout/" ....etc

I solved my issue update my magento nginx config

Replace #Line with below two line

#fastcgi_buffers 1024 4k; 
fastcgi_buffers 11024 16k;
fastcgi_buffer_size 32k;

Answer 4

In my case I am using docker in my local pc. I have have added these two configuration in the nginx.conf and it's working fine.

server {
    //......
    location ~ (index|get|static|report|404|503)\.php$ {
        //........
        fastcgi_buffers 16 16k;
        fastcgi_buffer_size 32k;
        //.......
    }
    //.......
}