Question

Error 502, Bad Gateway. DNS not pointing to correct IP.

Posted September 11, 2017 2.3k views
UbuntuMiscellaneous

Noob here, so please bare with me. A few months ago, I installed wordpress on Ubuntu. Everything was working fine. I got an email saying I needed to top up my DO account. Did that and that same day, I discovered the 502 error when trying to access my site. I didn’t touch or change any of the configurations so am confused as to why this is happening.

Checked the error log:
[Mon Sep 11 06:25:02.712692 2017] [mpm_prefork:notice] [pid 1561] AH00163: Apache/2.4.18 (Ubuntu) configured -- resuming normal operations
[Mon Sep 11 06:25:02.712766 2017] [core:notice] [pid 1561] AH00094: Command line: '/usr/sbin/apache2'

Checked the DNS and found out it’s not pointing to the correct IP where my droplet is. Double checked on the DO side and my domain (A record) is directed to the IP address of my droplet.

When I enter the IP address of my droplet in my browser, the same Error 502 comes up. I’ve waited a day, cleared out my cache, used a different browser etc, plus did a few reloads and still nothing.

What am I missing here? Desperate for a solution.

1 comment

These answers are provided by our Community. If you find them useful, show some love by clicking the heart. If you run into issues leave a comment, or add your own answer to help others.

×
Submit an Answer
1 answer

Hello,

In addition to what has already been mentioned, I would recommend following these steps in case that you are having any problems with your nginx server and you are unsure on what the problem is:

  • Check if nginx is running:
systemctl status nginx

If nginx is running you should see something like this:

● nginx.service - The nginx HTTP Server
   Loaded: loaded (/lib/systemd/system/nginx.service; enabled; vendor preset: enabled)
   Active: active (running) since Tue 2019-11-19 09:37:46 UTC; 2 days ago
     Docs: https://httpd.nginx.org/docs/2.4/

If nginx is not running then the output would look like this:

● nginx.service - The nginx HTTP Server
   Loaded: loaded (/lib/systemd/system/nginx.service; enabled; vendor preset: enabled)
   Active: inactive (dead) since Fri 2019-11-22 08:41:01 UTC; 39s ago
     Docs: https://httpd.nginx.org/docs/2.4/
  • If nginx is not running you could start it with:
systemctl start nginx

Then check the status agian and make sure that nginx remains running.

  • If nginx did not start after a reboot, you could enable it so that it starts after the next reboot:
systemctl enable nginx
  • Check your nginx config syntax:
nginx -t

If you get an error, you would need to fix that problem and then you could restart nginx:

systemctl restart nginx
  • If you get Syntax OK when running nginx -t then your confiruation is correct, so I would recommend checking your error logs:
tail -f /var/log/nginx/error.log
  • Check the permissions of the files and folders in your document root:

Find the user that your nginx service is running as:

ps auxf | grep nginx

If you are using Ubuntu, the user should be www-data, so you would need to make sure that your files and folders are owned by that user, so nginx could read and write to those files:

chown -R www-data:www-data /var/www/yourdomain.com
  • Check if nginx is binding to the default ports:
netstat -plant | grep '80\|443'
  • Check if ufw allows TCP connections on port 80 and 443:
ufw status

If this is the case, you can follow the steps from this article here on how to configure your ufw:

https://www.digitalocean.com/community/tutorials/how-to-set-up-a-firewall-with-ufw-on-ubuntu-18-04

That is pretty much it, with all of the above information you should be able to narrow down the problem.

For more information I would suggest checking out this article here:

https://www.digitalocean.com/community/tutorials/how-to-troubleshoot-common-site-issues-on-a-linux-server

And here is also a quick video demo on how to do that as well:

Hope that this helps!
Regards,
Bobby
Source: How to Troubleshoot Common Nginx Issues on Linux Server?

by Justin Ellingwood
Everybody runs into issues with their website at one point or another. This guide will help you troubleshoot some common issues and get your site running again.