502 Bad Gateway: Meaning, Causes, and How to Fix It

What is A Bad Gateway?

Have you ever seen a bad gateway error notification when trying to access a website page? Do you know what does that mean?

A bad gateway is an error that indicates that the gateway or proxy server received an invalid response from the upstream or backend server.

When you see a 502 bad gateway error, then some issues might arise when one website server tries to access or communicate with another server.

When you access website A, the first web server you visit needs to communicate with another server to retrieve specific data or information. 

Overall, it indicates that an error has occurred during the communication process between these servers.

If you encounter such an error notification when visiting a website, it signifies that the main web server cannot connect to the database server or another server needed to display that web page.

502 Bad Gateway Causes 

If you can't access a web page, it might be because the proxy or gateway server cannot fulfill the request from another server. Below are some common bad gateway causes you need to remember:

1. Disrupted Network Connection

One of the most common causes is a disruption in the network connection between the server acting as an intermediary (such as a proxy server or gateway) and the target server. 

Disruptions can occur for various reasons, including network overload, power outages, or technical issues in the network infrastructure. 

When the network connection is disrupted, the intermediary server cannot properly forward the request to the target server which then makes this error notification pop up.

2. Issues with Proxy or Gateway Server

The proxy or gateway server acts as an intermediary between the client (user) and the actual target server. 

Therefore, if both servers have problems, the data transmission process between the two parties will be hindered. 

Configuration errors on the server typically occur if the proxy server settings do not match the requirements or if there are errors in determining how to convey requests to the target server.

3. Timeout

Another 502 bad gateway cause is the timeout being exceeded. When a server sends a request to another server, both require time to complete the request. 

If the predefined time for the connection between servers expires before the request is completed, the intermediary server will generate some significant error code.

Typically, timeout issues arise due to a sudden and significant increase in the number of users or traffic on the website.

4. Incorrect Server Configuration

Incorrect server configuration processes can encompass various aspects, from hardware settings to software configuration.

Most importantly, if the proxy or gateway server is not configured correctly to forward requests to the target server.

5. Server Maintenance or Updates

When a website or web app undergoes routine maintenance or implements software updates, the target server may be unavailable for a while. 

Moreover, if there are changes to IP addresses, ports, or network structures, the proxy or gateway server may struggle to convey requests correctly. 

Therefore, when making infrastructure changes, it is essential to ensure that all server configurations remain compatible with those changes.

6. Strict Firewall Settings

Firewalls are responsible for protecting networks and servers from security threats. However, overly strict settings can sometimes block or hinder the connection between the server acting as an intermediary and the target. 

If security rules or the firewall deems the connection suspicious or violates certain security policies, the request will be denied. 

Additionally, if the intermediary server and the target server are in different networks, and firewall rules restrict communication between them, this error notification may also appear.

How to Fix A Bad Gateway

Now that you understand the meaning along with its causes, it's time for you to learn how to fix a bad gateway error to maximize your experience on the search engine.

Follow each step below!

1. Refresh the Error Page

Since this type of webpage error is often a temporary issue caused by network problems or server overload, the first solution is to refresh the page. 

This error is sometimes transient, and a simple refresh might resolve it. To be cautious, you can also check the website's availability and ensure it is not experiencing downtime using online tools.

2. Clear the Browser Cache

You can also address this error by clearing your browser cache. The cache stores temporary copies of web pages and other elements. 

Sometimes, a full cache can slow down the data retrieval process from the server. By clearing the browser cache, you can remove expired or corrupted copies.

3. Flush DNS

DNS (Domain Name System) functions as a translator between IP addresses and domain names. 

DNS cache typically stores this information to expedite the process of finding IP addresses when accessing specific websites. Flushing DNS involves cleaning or deleting the DNS cache.

Here are some steps you can follow:

• Open Command Prompt on your operating system.
• On Windows, search for "Command Prompt" in the Start menu and select "Run as administrator."
• Enter the command "ipconfig /flushdns" and press Enter.

4. Try on a Different Device or Browser

Sometimes, this issue may be related to device-specific configurations or problems. Therefore, you should try accessing the website on a different device or browser to see if the problem persists.

5. Check Your Plugins

Check the plugins enabled on the web server and disable them one by one to identify if any of them are causing the error.

If the error disappears after disabling a specific plugin, that plugin may need updating or replacing with a more stable alternative.

6. Check The CDN (Content Delivery Network)

CDN is a content distribution infrastructure that helps improve the speed of delivering web content by distributing it to servers worldwide. 

To resolve misconfigurations or technical issues you can start by verifying the CDN configuration and ensuring everything is set up correctly. Also, check logs and activity records in the control panel for warnings or errors that need fixing.

7. Check Error Logs

If the error code appears after an update or change, you definitely need to check the error logs. Perform this step according to the platform you are using. 

For example, in WordPress, you can check the error log by adding the following data structure to wp-config.php:

8. Contact Customer Support

If you have tried all the above methods and the bad gateway error persists, it is advisable to contact customer support and explain the chronology of the disruption to receive further guidance.