A 502 Bad Gateway error occurs when Cloudflare is unable to contact the origin web server.

As a part of our Server Management Services, our Support Engineers help webmasters to fix Cloudflare-related errors regularly.

Let us today discuss the possible reasons and fixes for this error.

What causes Cloudflare 502 error

Cloudflare returns an HTTP 502 or 504 error when the origin web server responds with a standard HTTP 502 bad gateway or 504 gateway timeout error.

To list out, some of the common reasons for this error include:

• Excessive server load
• Firewall restrictions

Let us now look at some possible steps that our Support Engineers follow to resolve this error.

How to fix Cloudflare 502 error

The exact steps to be followed to resolve the 502 error depend on the particular reason that triggered it.Some of those include:

1.Investigate excessive server load

The first step that our Support Engineers follow when they receive the 502 error is to investigate the server load. As this error generally triggers due to excessive server loads, crashes, or network failures, they cross-check these parameters initially.

We already have some articles discussing how to troubleshoot server load here.

We often see that the underlying cause for 502 errors can be service failures for web server, mysql server etc.

Also, we largely see 502 errors when the Web server in failed status. A simple restart of the httpd service will make the websites working again. To avoid recurrence, our Support Specialists go way further and fixes the real reason for web server failure.

2. Firewall restrictions

Most Web Hosting servers have built-in firewall to block traffic from bad networks. Additionally, some servers implement Country-based firewall blocks as well. That is, websites will be served only to users from selected countries.

In such cases, a user accessing the website from a blocked network will see 502 errors.

Here, our Support Engineers modify the server firewall in a way that does not create a security risk for the server.

Nowadays, many website owners rely on third-party content delivery networks for faster loading of images, videos etc. on the websites.

So this firewall modification also needs to accommodate these third-party content delivery networks as well.

Conclusion

The Cloudflare 502 error triggers when the origin web server responds with a standard HTTP 502 bad gateway or 504 gateway timeout error. This happens due to firewall restrictions and server resource issues. Today, we saw how our Support Engineers fix them.