Question

How to fix 502 Bad Gateway error message?

I was trying to upload a data file of around 600 MB in my project which is hosted in digital ocean. It tries to upload but 502 Bad Gateway Nginx error is shown.

While the upload completely works fine on my local system.

When I tried:

sudo tail -30 /var/log/nginx/error.log

It shows:

[error] 132235#132235: *239 upstream prematurely closed connection while reading response header from upstream, client: client's ip, server: ip, request: "POST /submit/ HTTP/1.1", upstream: "http://unix:/run/gunicorn.sock:/submit/", host: "ip", referrer: "http://ip"

After,

sudo nano /etc/nginx/sites-available/myproject

the nginx code

server {
    listen 80;
    server_name ip;
    client_max_body_size 999M;

    location = /favicon.ico { access_log off; log_not_found off; }
    location /static/ {
       alias  /root/static/;
    }
    location / {
        include proxy_params;
        proxy_pass http://unix:/run/gunicorn.sock;
    }
}

How to fix this?

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rikeshk012330 • January 11, 2021

Gunicorn is working. My memory logs are:


root@develop-110:~# free -m
              total        used        free      shared  buff/cache   available
Mem:           3936         354        2308          12        1272        3283
Swap:             0           0           0

Only with large file uploads, I have 502 gateway errors

Bobby Iliev • January 5, 2021

Hi there @rikeshk012330,

It looks like that your Gunicorn service has crashed and Nginx is unable to connect to it.

To fix the error you have to start the Gunicorn service.

For more information on how to troubleshoot 502 Nginx errors, I could suggest following the steps from this answer here:

https://www.digitalocean.com/community/questions/502-bad-gateway-nginx-2

Regards, Bobby