When i try to upload an image through my node express application running on Ubuntu 16.04, nginx directly gives me a 502 bad gateway. It doesn’t even take a second before it redirects to the 502.

It is supposed to upload the image to Cloudinary where i host my images and videos for my web application, and it is working perfectly on my local machine (localhost). But as soon as i tried from my droplet the error appears.

I don’t think it can be a problem with my ufw since i can easily create customers to stripe api, and everything else seems to work great.

Here is the error log from Nginx describing that the connection is closing prematurely:

2019/05/01 17:02:15 [error] 2063#2063: *6 upstream prematurely closed connection while reading response header from upstream, client: (IP LOCAL MACHINE), server: (DOMAIN), request: "POST /profile/5cc4$.........

2019/05/01 17:02:15 [error] 2063#2063: *6 connect() to [(IPV6]:8080 failed (101: Network is unreachable) while connecting to upstream, client: (IP LOCAL MACHINE), server: (DOMAIN), r$.....

And this is my nginx setup:

server {

        # SSL configuration
        # listen 443 ssl default_server;
        # listen [::]:443 ssl default_server;
        # Note: You should disable gzip for SSL traffic.
        # See: https://bugs.debian.org/773332
        # Read up on ssl_ciphers to ensure a secure configuration.
        # See: https://bugs.debian.org/765782
        # Self signed certs generated by the ssl-cert package
        # Don't use them in a production server!
        # include snippets/snakeoil.conf;

        root /var/www/html;

        # Add index.php to the list if you are using PHP
        index index.html index.htm index.nginx-debian.html;

        server_name where-can-i.org www.where-can-i.org;

        location / {
          proxy_pass http://localhost:8080;
          proxy_http_version 1.1;
          proxy_set_header Upgrade $http_upgrade;
          proxy_set_header Connection 'upgrade';
          proxy_set_header Host $host;
          proxy_cache_bypass $http_upgrade;
          proxy_buffer_size 1024k;
          proxy_buffers 4 1024k;
          proxy_busy_buffers_size 1024k;

    listen [::]:443 ssl ipv6only=on; # managed by Certbot
    listen 443 ssl; # managed by Certbot
    ssl_certificate /etc/letsencrypt/live/(DOMAIN)/fullchain.pem; # managed by Certbot
    ssl_certificate_key /etc/letsencrypt/live/(DOMAIN)/privkey.pem; # managed by Certbot
    include /etc/letsencrypt/options-ssl-nginx.conf; # managed by Certbot
    ssl_dhparam /etc/letsencrypt/ssl-dhparams.pem; # managed by Certbot

When i try to upload an image, it gives me the 502 bad gateway, and when i try to click “back” in the browser, it seems like it has restarted the pm2, cause i need to log in again. I have a middleware checking if you are logged in or not. I can’t seem to figure this one out myself, so i hope one of you have the knowledge. Everything works great on localhost to cloudinary but not from the droplet.

1 comment
  • @lefevreteam

    I am not sure if this can help but I think you need to put a / at the end of proxy_pass directive so it becomes like this:

     proxy_pass http://localhost:8080/;

    I sometimes had problems such because this / was missing.

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1 answer

@Mohsen47 - I have just tried it out, but it still gives the same error.

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