What is Error 400: Bad Request and How to Solve It

Have you ever received an Error 400: Bad Request message when trying to access a website? The 400 Bad Request error is an HTTP status code that indicates a problem with the website user’s request.

If you experience this error when opening a website, you don’t need to worry. How solve this problem is quite easy. In this article, we will provide solutions to resolve it. We will also provide information on the cause.

To find out more about error 400, what causes it, and how to fix it, let’s look at the description below!

Table of Contents

• What is Error 400: Bad Request?
• Cause 400 Error
• Display Error 400: Bad Request
• How to Overcome 400 Bad Requests
  • 1. Recheck URL
  • 2. Clear Browser Cache
  • 3. Delete Browser Cookies
  • 4. Flush DNS Cache
  • 5. Check File Size
• Conclusion

What is Error 400: Bad Request?

An error or 400 Bad Request error occurs when the server cannot understand a request from a website visitor (client). This server misunderstanding can occur because website visitors send the wrong request or the request sent is corrupt.

The important thing to understand is that error occurs on the client or website visitor side, not from the server. This error message is an indication that the client has sent a request that the server cannot process. However, in special cases, the server can also be the cause of the error.

Since the 400 error is more common on the client-side, the cause that we will discuss below will show the cause from the website visitor or client-side.

Cause 400 Error

Several things could be the reason why the Bad Request error message may appear in your browser. However, the majority of the causes are problems on the side of website visitors or clients. The causes of the 400 Bad Request error include:

• Invalid URL – Bad Requests can occur because the URL contains inappropriate or disallowed characters. The URL syntax might be wrong. URLs may contain invalid characters, such as [ , ] , { , and } . In addition, incorrect encoding can also contain ASCII characters that are used incorrectly.
• Corrupted browser cache or cookies – problematic browser cache files or outdated or corrupted cookies. Generally, this happens on a login page, such as the WordPress login page. If your log-in cookie is corrupted, you will not be able to log in because admin authentication is not provided.
• Problematic DNS cache – If a website changes hosting or domain name, the DNS cache records in your operating system may become problematic because they are invalid. The domain name change causes the locally stored DNS cache records not to match the DNS on the current website. This misalignment is what causes the 400 error message to appear.
• The file size is too large – Each server has its maximum file upload limit. If you upload a file whose size is more than that limit, your request will be considered a bad request and trigger an error. Simply put, the server cannot process a size that is too large than its maximum limit.

Display Error 400: Bad Request

Just like any other HTTP status code, the 400 Bad Request error message can appear on all browsers and devices you use. You can see it in Safari on macOS devices or in Google Chrome on Windows 10.

The 400 error message can appear in many variations. Websites can use multiple phrases to display the 400 error message. The Bad Request error message can appear with several other phrases, namely:

• HTTP Error 400
• Error 400
• Bad Request – Invalid URL
• 400 Bad Request
• HTTP 400 Bad Request
• 400 Bad Request Error
• HTTP Status 400 – Bad Request
• Bad Request: Error 400
• HTTP Error 400 – Bad Request
• Bad Requests. Your browser sent a request that this server could not understand.
• HTTP Error 400. The request hostname is invalid.
• 400 – Bad Requests. The request could not be understood by the server due to malformed syntax. The client should not repeat the request without modifications.

How to Overcome 400 Bad Requests

When you access a website, the computer will send a request or request to the webserver. After that, the server will process the request and send it back to the page you want to access in your browser.

Well, if in the process the server cannot understand the request that has been sent, instead of processing the request, the server will send an error code to you. If error 400 appears, you don’t have to worry. Several ways can be done to overcome it.

Here are some ways to deal with 400 Bad Requests that you can do.

1. Recheck URL

The easiest way is to double-check the domain address. The HTTP 400 error status could be due to a typo in the URL, invalid characters, and incorrect URL syntax. Typo in URL typing can be the cause of the error message.

If the URL contains directory paths, query strings, or file names, double-check whether the special symbols are correct or not. For example, a hyphen (-) or a percent (%).

2. Clear Browser Cache

If the website file that is in your browser locally is corrupted, a Bad Request error message may appear. Files that the browser saves locally can be HTML, text/config files, JavaScript, CSS, data files (XML, JSON), as well as media in the form of images, videos, and sounds.

Automatically, the browser has saved the above files when you first visit a website. Cache or stored files, efficiently help the browser work without the need to download the same file every time you visit the website.

If the cache in the browser is damaged, the Bad Request error message will certainly appear when you access a website. Therefore, you need to clear the browser cache so that the old corrupted data can be replaced with new data.

After you clear the browser cache, don’t forget to refresh the website you want to visit.

3. Delete Browser Cookies

If the Bad Request message still appears even after clearing the browser cache, you can try clearing browser cookies. One website can use many cookies, there are dozens of them. If any cookies are damaged or expired, a 400 Bad Request error will appear.

When an HTTP 400 error occurs because the web browser sends a cookie that is too large, the error message 400 Bad Request – Request Header or Cookie Too Large will appear. Thus, to solve the problem that arises, you need to delete browser cookies.

After deleting cookies, you can reopen the website showing the previous Bad Request message.

4. Flush DNS Cache

Apart from the browser cache, a corrupted DNS cache can also cause the 400 Bad Request error. Therefore, you must also flush the DNS cache or delete all DNS records on the computer.

When you open a website for the first time, the system will go through a DNS lookup or DNS lookup process. This process traces the nameservers and IP addresses associated with the domain name. After that, the operating system will store the IP address of the webserver in the DNS cache.

The next time you visit the same website, the system will skip the DNS lookup process. Finally, website loading becomes faster. 

However, if the DNS cache is problematic or not updating, an HTTP 400 error message may appear. Therefore, you must flush the DNS cache to update the DNS records.

5. Check File Size

As we discussed earlier, each server has a maximum file upload limit. If you try to upload a file whose size exceeds the website’s maximum limit, Bad Request: Error 400 will appear. Therefore, make sure that the file you upload does not exceed the maximum limit.

Not many websites mention the maximum file size that can be uploaded. Therefore, as the safest way, if you want to upload a file, try uploading a smaller file first. You can compress the file that you want to upload first.

Conclusion

You’ve learned that the HTTP 400 Bad Request error message is an error message that appears when a request to the server has a problem or is invalid. This error message occurs on the user side of the website, not on the server.

Since the problem is on the user’s side of the website, the client can easily solve the majority of the causes for the 400 Bad Request Errors. Some ways to solve this include:

• Recheck URL
• Clear browser cache
• Delete browser cookies
• Flush DNS cache
• Checking file size

After reading the description above, you don’t have to worry about the 400 error message anymore. Now, you can easily solve the 400 error because you already know how to solve it.

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