The HTTP Error 431 Request Header Fields Too Large is one of the HTTP status codes, which indicates that the origin server has refused to process a client’s requests. The reason for refusal is large HTTP headers. 

Whether you are an end user trying to access a website or a website owner where your users encounter HTTP Error 431, both are frustrating. Fortunately, the error code 431 provides some insights into what you need to fix. 

Here, in this blog post, I will walk you through some causes and solutions to troubleshoot the HTTP Error 431 Request Header Fields Too Large. 

Also, read about the 400 Bad Request Error, 403 Forbidden Error and 404 Not Found Error.

What is HTTP Error 431? 

As introduced above, HTTP Error 431 states that the server is not ready to process the client requests. This is due to the problem with HTTP request header fields. It means that the request header fields are too large in size. Basically, it is a client-side error and has nothing to do with the server. 

Though there is no restriction in the HTTP protocol for the maximum amount of data in requests, many servers limit the data size for security reasons. 

As a result, when the request headers or any one of the header fields is too large, you encounter HTTP Error 431. 

Causes of HTTP Error 431 Request Header Fields Too Large

As this error is client-side and not server-side, the problem is in your web browser. Now, you might be thinking, how is the web browser a cause for the error 431? This is because it is only the web browser that makes requests with large headers to the server. 

As a result, you need to make adjustments to your web browser in order to troubleshoot the HTTP Error 431. 

Common causes of HTTP error 431 include problems with cookies, lengthy referrer URLs, or simply the size of all the request headers.

If you are an end user trying to access the website and encounter error 431, you can resolve it by making adjustments to your web browser. However, if you are a website owner and don’t want your visitors to encounter this error, you need to inspect your website’s code. 

How To Fix HTTP Error 431? 

Now that you know the possible cause of this error. Let us now peek into some ways to troubleshoot this error. 

1. Clear Your Cookies and Browser Cache

Clearing cookies and browser cache serve as a solution to many browser and internet issues. 

Almost all websites leverage cookies to identify and store user-specific information. For instance, when you log into a website, it uses a cookie to remember you as a user and doesn’t require you to log in when you visit the website again. 

If there are a lot of cookies that result in large request header fields, you get HTTP Error 431. In such cases, clearing your cookies and browser cache will resolve the 431 error.

2. Shorten or Remove URL Query Parameters

The error 431 might also appear when attempting to access a website having URLs with lengthy query parameters. 

The portion of a URL that follows the “main” URL is the query parameters. Most of the time, we use query parameters to transmit extra information to the server, but they are not actually necessary to view the website.

In such cases, you need to remove all query parameters from the URL. 

Let us understand with an example. 

Base URL: 

URL with query parameters:

Simply delete the question mark and everything after it. Then, visit only the base URL to check whether the error has been resolved. 

3. Shorten/Edit Your Code

The current and the following solution will not help you if you are experiencing HTTP Error 431 on others’ websites. These solutions for your website.

The first approach is to examine the source code of your website to see if it’s producing a lot of request headers. Specifically, check to see if your code compels users’ browsers to send excessive queries. When using JavaScript, these errors occur a lot more frequently.

4. Adjust Cookie Settings

Your website’s cookie usage is another factor that could result in HTTP error 431. 

For instance, placing a lot of cookies in users’ browsers could result in an issue. This is one of the causes, and the reasons why deleting cookies from a website is a viable workaround. 

Make sure you’re not accidentally setting an excessive number of cookies to prevent this. This will require you to examine the source code of your website or to hire a qualified professional.

Also Read: What is 500 Internal Server Error & How to Fix it

Wrapping Up

The HTTP Error 431 Request Header Fields Too Large is a client-side error. It takes place when a client’s browser sends requests to the server that contain large request header fields.  

If the error occurs while visiting other’s websites, the most popular solution is to delete the cookies associated with that website from your browser. Additionally, you should check for the URL’s length due to query parameters. 

If the error takes place on your own website, you should probably check your code. Make sure you aren’t creating excessive amounts of request headers or cookie settings.

A passionate freelance technical writer with several years of experience specializing in crafting engaging technical content for a diverse range of businesses and platforms. With a track record of developing original, client-centric content, I excel at tailoring my writing to meet the unique needs of each project. Thorough research and attention to detail enable me to deliver content that not only meets but exceeds client expectations.


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