5XX Errors: A Guide to Understanding and Resolving Server Errors

As a website owner or developer, you may have encountered the infamous “500 Internal Server Error” or other 5XX server errors at some point.

These errors indicate that something has gone wrong on the server, preventing it from delivering the requested web page to the user’s browser.

In this article, we’ll explore the different types of 5XX server errors, their causes, and how to resolve them.

Introduction to HTTP Response Status Codes

Before we dive into the specifics of 5XX errors, let’s briefly go over HTTP response status codes. When you make a request to a website, the server responds with a three-digit code that indicates the status of the request. The most common codes are:

• 200 OK: The request was successful, and the server is returning the requested data.
• 300 Multiple Choices: The requested resource has multiple locations, and the server is returning a list of options.
• 400 Bad Request: The server could not understand the request due to a client error (e.g., malformed request syntax).
• 500 Internal Server Error: The server encountered an error while processing the request.

As you can see, 5XX errors fall into the category of server errors and indicate that the server was unable to fulfill the request due to an error on its end.

Do You Need to Worry About 5XX Server Errors?

In short, yes. 5XX server errors can have a negative impact on your website’s user experience and search engine rankings.

When users encounter 5XX errors, they may become frustrated and leave your site, leading to a higher bounce rate.

Additionally, search engines may interpret 5XX errors as a sign of poor website maintenance and may reduce your site’s visibility in search results.

Understanding 5XX Server Error Codes

There are several types of 5XX server errors, each with its own unique code and meaning. Let’s explore the most common ones:

Official 5XX Status Error Codes

500 Internal Server Error

The 500 Internal Server Error is the most common 5XX error and indicates that the server encountered an unexpected condition that prevented it from fulfilling the request. This can be caused by a variety of issues, such as coding errors, lack of server resources, or connectivity errors.

501 Not Implemented

The 501 Not Implemented error indicates that the server does not support the functionality required to fulfill the request. This can occur if the server does not recognize the request method (e.g., PUT or DELETE) or if it lacks the necessary resources to complete the request.

502 Bad Gateway

The 502 Bad Gateway error indicates that the server acting as a gateway or proxy received an invalid response from an upstream server. This can occur if the upstream server is offline, overloaded, or misconfigured.

503 Service Unavailable

The 503 Service Unavailable error indicates that the server is temporarily unable to fulfill the request due to maintenance, high traffic, or other reasons. This is a common error during peak traffic periods or server maintenance.

504 Gateway Timeout

The 504 Gateway Timeout error indicates that the server acting as a gateway or proxy did not receive a timely response from an upstream server. This can occur if the upstream server is overloaded or slow to respond.

505 HTTP Version Not Supported

The 505 HTTP Version Not Supported error indicates that the server does not support the HTTP version used in the request. This can occur if the client is using an outdated or unsupported version of HTTP.

506 Variant Also Negotiates

The 506 Variant Also Negotiates error indicates that the server has an internal configuration error and is unable to complete content negotiation.

507 Insufficient Storage

The 507 Insufficient Storage error indicates that the server does not have enough storage space to complete the request. This can occur if the server is overloaded with too many requests or if there is a problem with the server’s storage capacity.

508 Loop Detected

The 508 Loop Detected error indicates that the server detected an infinite loop while processing the request. This can occur if there is a problem with the server’s configuration or if there is a coding error that causes the server to loop endlessly.

509 Unassigned

The 509 Unassigned error is an unassigned code in the official HTTP status code registry and is not currently used.

510 Not Extended (Obsoleted)

The 510 Not Extended (Obsoleted) error indicates that the server does not support the extension requested in the request. This code has been obsoleted and is no longer in use.

511 Network Authentication Required

The 511 Network Authentication Required error indicates that the client needs to authenticate to gain network access. This can occur if the server requires a specific authentication method or if the client does not have the necessary credentials to access the network.

512 – 599 Unassigned

Codes 512 to 599 are currently unassigned in the official HTTP status code registry.

Unofficial 5XX Status Codes

In addition to the official 5XX error codes, there are also several unofficial codes used by specific services or platforms. Here are a few examples:

Amazon Web Services

Amazon Web Services uses the 561 Unknown Error code to indicate that there is a problem with “Elastic Load Balancer.”

Apache / cPanel

Apache and cPanel use the 508 Resource Limit Is Reached error to indicate that the server has exceeded its resource limits.

Cloudflare

Cloudflare uses the 521 Web Server Is Down code to indicate that the origin server has stopped responding.

Pantheon

Pantheon uses the 503 Backend Fetch Failed error to indicate that the server was unable to fetch the requested data from the backend.

Qualsys

Qualsys uses the 599 Network Connect Timeout Error code to indicate that the server timed out while waiting for a network connection.

Other Unofficial 5xx Status Codes

There are many other unofficial 5XX error codes used by various services and platforms. If you encounter an error code that is not listed here, consult the documentation for the service or platform in question to determine its meaning.

How to Find Pages Returning a 5XX Server Error on Your Website

Now that you understand the different types of 5XX errors, how do you find pages on your website that are returning these errors? Here are a few methods:

Google Search Console

Google Search Console is a free tool that allows you to monitor your website’s performance in Google search results. It also provides a report of any errors Google encountered while crawling your site, including 5XX server errors.

Website Crawlers

There are many website crawlers available that can scan your entire site and identify any pages that are returning 5XX errors.

Some popular options include:

• Screaming Frog
• Ahrefs
• SEMrush

Website Monitoring

You can also use a website monitoring service to monitor your site’s uptime and receive alerts if any pages return 5XX errors.

Some popular options include Pingdom, UptimeRobot, and Site24x7.

Common Causes of 5XX Server Errors

There are several common causes of 5XX server errors, including:

Coding Errors

Coding errors in your website’s backend can cause server errors, especially if they result in infinite loops or other issues that overload the server.

Lack of Server Resources

If your website receives a high volume of traffic or if you have limited server resources, you may encounter 5XX errors.

Connectivity Errors

If there is a problem with the connection between your server and the client’s browser, you may encounter 5XX errors. This can occur if the connection is interrupted or if there is a problem with the server’s network.

Errors in .HTACCESS File

If your website uses an .htaccess file to manage server configuration, errors in this file can cause 5XX errors.

Bug in WordPress Plugin or Theme

If your website is built on the WordPress platform, a bug in a plugin or theme can cause 5XX errors.

Conclusion

5XX server errors can be frustrating for website owners and users alike, but understanding their causes and how to resolve them can help keep your website running smoothly. By monitoring your website for 5XX errors, identifying the root cause of any issues, and taking steps to address them, you can minimize the impact of these errors on your website’s performance and user experience.