How to Fix 502 Bad Gateway Error? (Ultimate Guide)

What is a 502 Bad Gateway Error?

The HyperText Transfer Protocol HTTP 502 Bad Gateway error usually comes from the server end and doesn’t have anything to do with your computer locally. This error states there has been an inadequate response from the other server. You can see this error on any device, browser, and operating system.

This error page can be modified by every website, in which case you will see a custom error page instead of the default error page above. Some other common server-side errors that you see are 504 Gateway Timeout Error, Error 500 internal server error, and dns_probe_finished_nxdomain.

502 bad gateway
502 bad gateway error

You might find multiple variations of 502 Bad Gateway Error on different sites. For example:

  • HTTP Error 502- Bad Gateway
  • 502 Proxy Error
  • 502 Bad Gateway
  • 502 Service Temporarily Overloaded
  • HTTP 502
  • 502 Bad Gateway NGINX
  • Error 502

Nginx is a well-known open-source web server that is highly popular for its performance, scalability, and flexibility. However, similar to other web servers, Nginx can face errors that hinder its ability to deliver content to clients. One such error is the 502 Bad Gateway Nginx error.

Encountering errors can be quite frustrating and confusing, especially if you are not technically proficient. You may come across several similar prominent errors, such as the white screen of death, and the error establishing database connection. But 502 bad gateway nginx error is a very popular one.

Let us get started!



How to Fix a 502 Bad Gateway Error?

There are numerous things that you can try to resolve this problem. Mostly, the 502 errors are the result of bugs in the PHP or the Server configuration or network errors among servers. There is nothing wrong with your computer or your internet connectivity.

Nonetheless, in some cases, there might be a problem at your end with the browser, or your ISP or local IP might be blocked as mentioned earlier. With these fixes, you can try and resolve the 502 error.

Common Fixes Of 502 Bad Gateway Errors (For Users)

Check out the below-listed solutions for 502 Bad Gateway Error for users.

1. Refresh the webpage

When experiencing a 502 error, there are chances that the server of the website might be overloaded with a higher amount of traffic than it can’t handle. If this is the case, you can try to fix this by simply refreshing the webpage.

Alternatively, you can also press the keys Ctrl + R or F5 to refresh/reload the page. This error means there is a networking error that is beyond your control, so it can be a temporary error while the server is getting a large amount of traffic or the server could be under a DDOS attack. By trying again in a while, you might not see this again.

Reloading webpage to fix 502 bad gateway
Reloading the web page

2. Try in Incognito Mode

Fixing 502 bad gateway error in Incognito mode
Incognito mode

Another way to fix this error is by starting a new Private or Incognito session in your browser. All you have to do is just close the existing tabs and open a new Private or Incognito window. If you experienced this error because of an issue on your browser, then starting your browser again in private mode should resolve the issue.

3. Clear the Cache Memory of your Browser

There is a chance that the corrupted files stored on your browser might be causing a 502 bad gateway error. So, if you clear the cache of your browser, you might resolve this error. Moreover, you should remove the cookies from your browser. It can also help in resolving this error.

Clearing browser data in chrome
Clearing Browsing data

4. Try Another Browser

You can try to use another browser such as Chrome, Safari, Firefox, and Internet Explorer. If you don’t see this error when you change your browser, this indicates that the problem was in the browser. You can even reinstall the browser to check if this resolves the problem.

5. Check Your DNS

Another solution for this error is by checking your domains’ DNS records. Sometimes the Bad Gateway error is caused by problems associated with DNS records. If you have not changed the DNS records, then you can also check if the IP in the records is set correctly and if there is no typo there.

6. Restart Your Network Device

First of all, You need to switch off the power supply of your internet modem. To do this, Unplug your internet modem and hold it up for 10 seconds. When its indicators are completely turned off,  You need to plug it in again turn on the power on button, and Wait for your computer to establish a connection again.


Read: 🚩 How to fix HTTP 500 Internal Server Error in WordPress?


Common Fixes For 502 Bad Gateway Error (Developers)

If you are a developer or a server manager facing this error, there are chances that you might be facing this error because of other factors. You can try these solutions to eliminate the problem.

1. Clear Local DNS cache

You can also try to clear the DNS cache to see if this issue resolves or not. To do this you need to open your cmd prompt for Windows users. 

Open the command prompt on your Windows PC and type ipconfig / flushdns then press Enter:

502 bad gateway
Command prompt

2. Check Error Logs:

You can also check the server or site error logs created on the server to check if there is any particular error being thrown on the server. Using this error you can then try and resolve the issue. If you are a WordPress user you need to add the following codes in your  wp-config.php

  • By doing this you will get all the information regarding the errors that have occurred due to any recently added application. And you will get all the causes of the errors which are produced by your website.

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

Read: How to Set up and Use WordPress Error Log?

3. Check Plugins and themes on your WordPress

For WordPress sites, you can temporarily rename the wp-content/plugins folder to rule out any error due to any plugin on the site. In case the issue is not due to the plugins, you can also check for the theme by downloading the default WordPress theme and switching over to that. In case the site loads fine after activating the default theme, then the issue might be due to your theme.

4. Disable CDN Temporarily

Another reason could be that the server is being targeted by a DDOS attack. In such cases, you may use services like Fail2ban to try and block the attacking IPs or you can use CDN providers like Cloudflare, to mitigate any DDOS attacks on the server. On the other hand, sometimes the 502 bad gateway error also triggers due to an issue with your CDN or firewall itself. These CDN providers or fully proxy services have extra firewalls between them, that help to protect against DDOS attacks.

How to fix 502 Bad gateway Nginx Error?

Nginx is a well-known open-source web server that is highly popular for its performance, scalability, and flexibility. However, similar to other web servers, Nginx can face errors that hinder its ability to deliver content to clients. One such error is the 502 Bad Gateway Nginx error.

Encountering errors can be quite frustrating and confusing, especially if you are not technically proficient. You may come across several similar prominent errors, such as the white screen of death, and the error establishing database connection. But 502 bad gateway nginx error is a very popular one.

Here are some of the methods you can try to fix it.

1. Check the status of Nginx

The first thing you need to do is to check whether Nginx is running and responding to requests or not. To do that, run the following command given below:

systemctl status nginx

If the Nginx is running, you will get an output message something like this,

nginx.service - The nginx HTTP Server
Loaded: loaded (/lib/systemd/system/nginx.service; enabled; vendor preset: enabled)
Active: active (running) since Wed 2022-10-11 10:25:41 UTC; 1 days ago
Docs: https://httpd.nginx.org/docs/2.4/

If the Nginx is not running, you will get an output message something like this,

nginx.service - The nginx HTTP Server
Loaded: loaded (/lib/systemd/system/nginx.service; enabled; vendor preset: enabled)
Active: inactive (dead) since Fri 2022-10-11 10:25:41 UTC; 25s ago
Docs: https://httpd.nginx.org/docs/2.4/

Now, in case the Nginx is not running, you have to start it again by using the following command,

systemctl start nginx

2. Check the Backend Server Status

  • Log in to the reverse proxy server that is hosting Nginx.
  • Open a terminal window and run the following command:

curl -I http://backend-server-ip-address/

• Replace “backend-server-ip-address” with the IP address of your backend server.

• Check the HTTP status code in the output of the command. If the backend server is running correctly, you should see a status code of 200 OK.

• If you receive a status code other than 200, it indicates that there may be an issue with the backend server. You can further investigate the issue by examining the logs of the backend server to identify any errors or warning messages.

3. Check the DNS Configuration

If the DNS resolution fails, the reverse proxy server cannot forward the request to the backend server, resulting in a 502 Bad Gateway error being returned to the client. Therefore, it is important to verify that the DNS configuration for the backend server is correct.

To check the DNS configuration, you can perform the following steps:

  • Log in to the reverse proxy server that is hosting Nginx.
  • Open a terminal window and run the following command:

nslookup backend-server-domain-name

Replace “backend-server-domain-name” with the domain name of your backend server.

• Check the output of the command to verify that the correct IP address is returned for the backend server.

  • If the output of the command indicates that the DNS resolution failed, there may be an issue with the DNS configuration. You can further investigate the issue by checking the DNS settings for the domain name of the backend server, or by contacting your DNS provider for assistance.

4. Check the Firewall Configuration

It is advised to check the firewall logs for an unusual block. Sometimes Firewalls also prevent or block sites. To overcome this issue, you need to temporarily disable your firewalls and check whether the issue persists or is resolved.

5. Increase the Buffer Size

Increasing the buffer size allows Nginx to store more data from the server’s response, ensuring that the response is complete and error-free. To increase the buffer size, you need to edit the Nginx configuration file and add the following directives.

  • proxy_buffer_size: Sets the size of each buffer. The default value is usually 4K. You can increase it to a higher value depending on your server’s requirements. For example, to set the buffer size to 16K, add the following line to your configuration file:

proxy_buffer_size 16k;

  • proxy_buffers: Sets the number of buffers to allocate. The default value is usually 8. You can increase it to a higher value depending on your server’s requirements. For example, to set the number of buffers to 32 and the buffer size to 16K, add the following line to your configuration file:

proxy_buffers 32 16k;


Note: It’s important to note that increasing the buffer size and number of buffers will increase memory usage on the server. So, you should experiment with different buffer sizes and buffer numbers to find the optimal setting for your server and application.


  • After making changes to the Nginx configuration file, save the file and restart Nginx for the changes to take effect. You can do this by running the following command:

sudo service nginx restart

6. Restart Nginx Server

In some cases, just restarting the Nginx server may resolve the 502 bad gateway Nginx error. To do this,

You need to run a command in your terminal or shell. The exact command depends on the operating system and distribution you are using, but here are a few examples:

  • Ubuntu and Debian:

sudo service nginx restart

  • CentOS, Fedora, and RHEL:

sudo systemctl restart nginx

  • macOS:

sudo nginx -s reload

These commands will gracefully restart the Nginx server, meaning that it will wait for any active connections to finish before shutting down and starting again.

7. Check PHP-FPM Status

Sometimes, the 502 Bad Gateway Nginx error can also be triggered by PHP-FPM not running. Therefore, it is necessary to check the status of PHP-FPM to ensure it is running properly.

To check the running status, you can use the following command,

sudo service php-fpm status

If PHP-FPM is running, you should see a message stating that it is active.

However, in case PHP-FPM is not running, you can try restarting it using the following command:

sudo service php-fpm restart

This command will restart the PHP-FPM service, which can help resolve any issue that might be triggering a 502 bad gateway Nginx error.


Read: 🚩 15 Methods to Fix 502 Bad Gateway Error on Your Website


What Causes a 502 Bad Gateway Error?

There can be several reasons why a 502 Bad Gateway error may occur, but here are some of the most common ones listed below:

1. Server Overload

When a backend server receives too many requests, it can become overloaded and fail to respond within the timeout period. This causes a 502 error as the upstream server cannot fulfill the client’s request. Proper server sizing, resource allocation, load balancing, and scaling strategies can prevent server overload. This is why we highly recommend you switch to a more robust and fastest WordPress dedicated hosting.

2. Connectivity Issues

  • Connectivity issues can cause a 502 Bad Gateway error when there is a problem with the network connection between the reverse proxy server and the backend server.
  • This can happen due to network congestion, misconfigured network settings, or hardware failures.
  • When the reverse proxy server attempts to forward a request to the backend server but cannot establish a connection, it returns a 502 error to the client.
  • The error occurs because the reverse proxy server acts as an intermediary between the client and the backend server and is unable to connect to the backend server to fulfill the client’s request.
  • Troubleshooting network settings, checking firewall rules, and monitoring network traffic can help fix the issue.

3. DNS Issues

  • DNS issues can cause a 502 Bad Gateway error when the DNS resolution for the backend server fails.
  • This can happen due to incorrect DNS configurations, DNS server failures, or DNS caching issues.
  • When a client sends a request to the reverse proxy server, the reverse proxy server needs to resolve the domain name of the backend server to an IP address.
  • If the DNS resolution fails, the reverse proxy server cannot forward the request to the backend server, resulting in a 502 error being returned to the client.

Read: 🚩 What is DNS?


4. Firewall Restrictions

  • Firewall restrictions can cause a 502 Bad Gateway error when a firewall blocks the connection between the reverse proxy server and the backend server.
  • This can happen when the firewall is configured to restrict traffic to and from specific IP addresses or ports.
  • When the reverse proxy server attempts to connect to the backend server, but the firewall blocks the connection, it returns a 502 error to the client.
  • This occurs because the reverse proxy server acts as an intermediary between the client and the backend server and cannot establish a connection with the backend server to fulfill the client’s request.
  • To fix firewall-related issues causing a 502 error, you may need to adjust firewall rules to allow traffic to flow between the reverse proxy and backend servers.

5. Software Bugs

  • A 502 Bad Gateway error may occur due to a software bug or misconfiguration in the reverse proxy server or backend server.
  • This error can happen because of coding errors or misconfigurations of server modules or applications.
  • If the software or configuration of either server contains a bug, it may fail to handle requests or respond within the timeout period, resulting in a 502 error being returned to the client.
  • To fix software-related issues causing a 502 error, you may need to examine the logs of both the reverse proxy and backend servers to identify any errors or warning messages.

6. PHP-FMP is Taking too long to respond

  • PHP-FPM (FastCGI Process Manager) can cause a 502 Bad Gateway error when it fails to respond within the timeout period or encounters a critical error.
  • This error can happen due to insufficient resources, misconfiguration, or a bug in the PHP code.
  • PHP-FPM is a popular way of running PHP applications, where Nginx sends the request to PHP-FPM and it processes the PHP code and returns the result to Nginx, which then sends the response back to the client.
  • To fix PHP-FPM-related issues, you may need to adjust the PHP-FPM configuration to increase the number of processes or threads or adjust the timeout settings.
  • You may also need to examine the PHP code to identify and fix any bugs or performance issues.
  • Additionally, monitoring the server logs and system resources can help identify any patterns or trends that could indicate a larger issue with PHP-FPM.

7. Server Failure

You might experience a 502 error if the server has completely failed. It can be due to a system crash or sometimes the server is taken offline for maintenance or similar reasons. This can also be because the content of the server might be violating the server provider’s terms and conditions.

8. Error In Browser

Sometimes, some browser extensions can also lead to errors while rendering the website, particularly AdBlock extensions. Apart from this, rare cases might cause the error due to the browser version being outdated.


Read: 🚩 How to Fix HTTP 504 Gateway Timeout Error?


Impact of 502 Bad Gateway Errors on the SEO of Your Website

If this error displays on your computer screen, again and again, it will have a bad impact on your website’s reputation as well as on the Search Engines. In the end, it leads to a poor experience for the clients on a clear basis that, nobody needs to manage a site that as often as possible shows errors.

If this error remains too long on your website, probably your website will be completely deindexed on the search engines as your website will not show any data to people leading to high bounce rates and dropping ranks.


Server failure and poor server management are two major reasons for triggering 502 bad gateway errors. You can stop this in the future by simply hosting or migrating your website to the most reliable and reputed Fully Dedicated WordPress host, WPOven.


Too many 502 error issues
WPOven

Summary

As you can see from the above post, there are sufficient methods available combining both user and developer-friendly available, With the help of which you can troubleshoot and try to fix a 502 bad gateway error on your WordPress site.

Since this error triggers from the server side rather than the client side. It means the problem is not coming from either your website, computer, or internet connection. However, you should not forget to check out your third-party plugins or themes for bad codes or misconfigured files.

We hope the methods mentioned in this post to fix 502 bad gateway errors will help you to bring your website to normal just like it was before the error. If you have any more methods or solutions, that we haven’t covered in this post, feel free to let us know in the comment section below.


Read: 🚩 How to fix HTTP 500 Internal Server Error in WordPress?


Frequently Asked Questions

How do I fix Error 502?

You can fix Error 502 by doing the following methods:
Refresh your browser and reopen it: First, you need to close your current browser hold up a couple of moments, and reopen it. It is because Sometimes your browser may stop responding due to accessing the heavy traffic of data at the same time or maybe an error page is inserted in between the pages which are loading. Even try on another browser as well.
Reset Internet configuration: You need to restart your Internet modem. to do this, Unplug your internet modem and hold it up for 5 seconds, after it completely turns off, Plug it in again and Wait for your computer to establish a connection again.
Disable CDN temporarily: The Content Delivery Network commonly known as CDN improves the loading speed of a website but it can generate error 502 as well due to the firewalls. To overcome this issue, you can disable the CDN temporarily.

What causes 502 Bad Gateway Nginx?

A 502 error happens when one web server gets a response that is not valid from another web server. The servers that communicate do not agree on the protocol for exchanging information. This sort of error is normally for a short period, so we can later attempt to enter the web once more. More often, the issue is on the website itself, and there’s very little you can do. But, this 502 Bad Gateway Nginx error can happen due to an issue on your PC or your internet hotspot device.
The following are some reasons:
1. Browser configuration problem
2. Server overloaded
3. not correctly configured servers
4. Error in communication between two servers

What is a 502 Bad gateway error?

A 502 Bad Gateway Nginx error is an HTTP status code that represents a server acting as a gateway or proxy server failing to receive a valid response from an upstream server.


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