How to Fix a 502 Bad Gateway Error on Your WordPress Site

By , Updated: September 20, 2017

502 bad gateway

When it comes to WordPress, there are a lot of different errors that can be downright frustrating and confusing. A few that come to mind are the white screen of death or the frightening error establishing a database connection. But an even more popular one is the 502 bad gateway error. Why? Because this regularly happens around the entire web, not only to WordPress sites, but even popular services such as Gmail, Twitter, and Cloudflare. But of course, we really only care about how it impacts your WordPress site. Read more below about what causes this error and some solutions on how to quickly resolve it.

What is a 502 Bad Gateway Error?

Every time you visit a website your browser sends a request to a web server. The web server receives and processes the request, and then sends back the requested resources along with an HTTP header and HTTP status code. Typically an HTTP status code isn’t seen unless something goes wrong. It’s basically the servers way of notifying you that something has gone wrong, along with the code on how to diagnose it.

There are many different types of 500 status error codes (500, 502, 503 504, etc) which all have slightly different meanings. These indicate that the request was accepted, but the server prevented the fulfillment of the request. In this case, a 502 bad gateway error specifically means that one server, while acting as a gateway or proxy, has received an invalid response from an inbound server (RFC 7231).

502 bad gateway error in browser
502 bad gateway error in browser

502 Bad Gateway Error Variations

Due to the various browsers, web servers, and operating systems, a 502 bad gateway error can present itself in a number of different ways. But they all have the same meaning. Below are just a couple of the many different variations you might see on the web:

  • “502 Bad Gateway”
  • “Error 502”
  • “HTTP Error 502 – Bad Gateway”
  • “502 Service Temporarily Overloaded”
  • “502 Proxy Error”
  • “502 Server Error: The server encountered a temporary error and could not complete your request”
  • “HTTP 502”
  • “502. That’s an error. The server encountered a temporary error and could not complete your request. Please try again in 30 seconds. That’s all we know.”

Other services such as Twitter might even show a completely different message for a 502 Bad Gateway error, such as “Twitter is over capacity.” This definitely looks a little more user-friendly.

Twitter is over capacity
Twitter is over capacity (Img src: Softpedia)

How to Fix the 502 Bad Gateway Error

A 502 bad gateway error is typically a problem with the network/server, however, it can also be a client-side issue. So we’ll dive into a little of both. Check out these common causes and ways to fix the 502 bad gateway error to and get back up and running.

1. Try Reloading the Page

One of the easiest and first things you should try when encountering a 502 bad gateway error is to simply wait a minute or so and reload the page (F5 or Ctrl + F5). It could be that the host or server is simply overloaded and the site will come right back. While you’re waiting, you could also quickly try a different browser to rule that out as an issue.

Another thing you can do is to paste the website into downforeveryoneorjustme.com. This website will tell you if the site is down or if it’s a problem on your side.

downforeveryoneorjustme
downforeveryoneorjustme

2. Clear Your Browser Cache

Whenever you encounter issues like these it can be good to clear your browser cache. Below are instructions on how to do it in the various browsers:

3. DNS Issue

A 502 gateway error could also be because of a DNS issue, such as the domain is not resolving to the correct IP. If you have just migrated your WordPress site to a new host, is it important to wait for things to fully propagate, which can take up to 24 hours in some cases. This depends upon the TTL value of your DNS records.

You can also try flushing your local DNS cache. This is similar to clearing your browser cache.

In Windows simply open up Command Prompt and enter the following:

ipconfig /flushdns
Command prompt - flush DNS
Command prompt – flush DNS

You should see a “Successfully flushed the DNS resolver Cache” if it worked.

For macOS users, you can enter the following in the terminal:

dscacheutil -flushcache

Note: There is no success message on Macs.

And lastly, you could temporarily change your DNS servers. By default, DNS servers automatically assigned by your ISP. But you could try temporarily changing these to a public DNS server, such as Googles. In fact, some prefer to use Google’s public DNS long-term.

4. Check With Your Host

The primary reason we typically see a 502 bad gateway error is due to an issue with the web host. Sometimes a query, script, or request will take too long and so it is canceled or killed by the server. A lot of hosts, especially shared hosts implement what they call a “kill script.” Basically what this does is it will terminate a request after a certain period of time so that it doesn’t take a site down or impact other users. If you do a Twitter search for “bad gateway” you can see thousands of tweets happening every day alerting their hosting company of the problem.

502 bad gateway tweets
502 bad gateway tweets

One reason you might want to consider moving to a host like Kinsta is that our platform runs in an isolated software container that contains all of the software resources required to run the site (Linux, NGINX, PHP, MySQL). This means that the software that runs each site is 100% private and is not shared, even between your own sites. This greatly reduces the chance of seeing a 502 bad gateway error. We aren’t running aggressive kill scripts like some shared hosts are. And even if one of your sites does happen to go down, it won’t impact your other sites.

Another reason you could see a 502 gateway error with your host is also due to the fact that the server is simply not reachable, either because it is down or there is no connectivity. In this case, it is recommended to check your WordPress host’s status page or open a support ticket.

5. Temporarily Disable CDN

It could also be an issue with your content delivery network (CDN). If you are using a 3rd-party CDN provider an easy way to troubleshoot this is to simply disable your CDN temporarily. For example, we are big fans of the free CDN enabler plugin. If you are using that, you can simply deactivate the plugin and then test your site. If you can’t access your site’s dashboard, simply log in to your site via SFTP and rename the plugin’s folder to cdn-enabler_old. This will temporarily disable the CDN connection. The same goes for WP Rocket or any other plugin you might have hooked up to your CDN.

Rename plugin folder temporarily
Rename plugin folder temporarily

This can also occur sometimes with providers that provide DDoS protection and mitigation or fully proxy services like Cloudflare, as they have extra firewalls in-between. We have noticed that this happens once in a while on the Cloudflare free plan. Unfortunately, since Cloudflare is a fully proxy service, there is no quick way to simply disable it.

However, before you go blaming Cloudflare, it is important to know that there are two different types of 502 bad gateway errors variations with Cloudflare as seen below:

502 Bad Gateway at Cloudflare (Variation 1)

If you see the following screen, this is actually a problem on Cloudflare’s end, in which case you should reach out to them for support.

Cloudflare 502 bad gateway
Cloudflare 502 bad gateway (Img src: Cloudflare)

502 Bad Gateway at Cloudflare (Variation 2)

If you see the following screen, this is a problem with your host.

Cloudflare 502 bad gateway at host
Cloudflare 502 bad gateway at host

6. Check Your Plugins and Themes

A lot of times the reason for scripts and queries being canceled by the server is due to bad code on your WordPress site, possibly from a 3rd party plugin or theme. We have also seen a lot of misconfigured caching plugins generate 502 errors. A few ways you can troubleshoot this is by deactivating all your plugins. Remember, you won’t lose any data if you simply deactivate a plugin.

If you can still access your admin, a quick way to do this is to browse to “Plugins” and select “Deactivate” from the bulk actions menu. This will disable all of your plugins. If this fixes the issue you’ll need to find the culprit. Start activating them one by one, reloading the site after each activation. When you see the 502 gateway error return, you’ve found the misbehaving plugin. You can then reach out to the plugin developer for help or post a support ticket in the WordPress repository.

Deactivate all plugins
Deactivate all plugins

If you can’t access your admin you can FTP into your server and rename your plugins folder to something like plugins_old. Then check your site again. If it works, then you will need to test each plugin one by one. Rename your plugin folder back to “plugins” and then rename each plugin folder inside of if it, one by one, until you find it.

Rename plugin folder
Rename plugin folder

Always makes sure your plugins, themes, and WordPress core are up to date. And check to ensure you are running a supported version of PHP. You can always reach out to your host for assistance. We utilize New Relic and other troubleshooting methods here at Kinsta to help clients narrow down what plugin, query, or script might be causing the error. You can also use your own custom New Relic key.

Time consuming queries to database
Time-consuming queries to database

If it turns out to be an efficient query or bad code in a plugin, you might need to bring in a WordPress developer to fix the issue.

7. Check Logs

You should also take advantage of your error logs. If you are a Kinsta client, you can easily see errors in the log viewer in the MyKinsta dashboard. This can help you quickly narrow down the issue, especially if it’s resulting from a plugin on your site.

Check error logs for 502 bad gateway errors
Check error logs for 502 bad gateway errors

If your host doesn’t have a logging tool, you can also add the following code to your wp-config.php file to enable logging:

define( 'WP_DEBUG', true );
define( 'WP_DEBUG_LOG', true );
define( 'WP_DEBUG_DISPLAY', false );

The logs are typically located in the /wp-content directory. Others, like here at Kinsta might have a dedicated folder called “logs”.

wordpress error logs folder sftp

You can also check the log files in Apache and NGINX, which are commonly located here:

  • Apache: /var/log/apache2/error.log
  • NGINX: /var/log/nginx/error.log

If you are a Kinsta client you can also take advantage of our analytics tool to get a breakdown of the total number of 502 errors and see how often and when they are occurring. This can help you troubleshoot if this is an ongoing issue, or perhaps something that has resolved itself.

Response analysis 500 error breakdown
Response analysis 500 error breakdown

Summary

As you can see there are quite a few things you can do to troubleshoot and fix a 502 gateway error on your WordPress site. Typically this is not on the client-side, but rather an issue with your host. Third-party plugins and themes with bad code or unoptimized queries are also things to watch out for. Was there anything we missed? Perhaps you have another tip on troubleshooting 502 gate errors. If so, let us know below in the comments.