Question

502 Bad Gateway

Posted on November 4, 2023
Ubuntu 22.04
Asked by Kevin Mwangi

I have used this tutorial here to deploy my Nodejs application. I have followed up on everything correctly but I noted when I edited my location / on my server block in this file /etc/nginx/sites-available/example.com file from this,

location / {
    try_files $uri $uri/ =404;
}

to this

    location / {
        proxy_pass http://localhost:5000;
        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;
    }

I get a 502 Bad Gateway error on my website. Can someone help me fix that?

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Bobby Iliev

Site Moderator

• November 9, 2023

Hello,

The “502 Bad Gateway” error often indicates that Nginx is unable to communicate with the upstream server, in this case, your Node.js application running on port 5000.

Here are a few things that you should check:

Ensure that your Node.js application is running and correctly listening on localhost:5000. You can check this with the command netstat -plant | grep 5000 from the server’s terminal.
If your application is not listening on port 5000, you would need to change the proxy rule in your Nginx configuration to match the port that your app is listening on. Also, verify that your Nginx configuration for proxying is correct and there are no typos. The configuration you’ve posted looks correct, but ensure there are no conflicting server blocks. You can use the nginx -t command to do a quick Nginx config test.
Look at both the Nginx error logs (/var/log/nginx/error.log) and your Node.js application logs to see if there are any reported issues that could be causing the error.

Here is a quick video that also might be helpful!