Bad Request Error in WordPress
Bad Request Error in WordPress

Understanding and Resolving the 400 Bad Request Error in WordPress


If you own a WordPress website, you’ve likely encountered the frustrating 400 Bad Request error at some point. This error can be particularly vexing, whether you’re a newcomer to the platform or an experienced user. In this comprehensive guide, we will delve into the intricacies of the 400 Bad Request error in WordPress, exploring its causes and providing solutions to get your website up and running smoothly.

What is the 400 Bad Request Error?

The 400 Bad Request error, often simply referred to as “400” or “HTTP 400 error,” indicates that the request sent to access a website has encountered an issue. This error arises when the data flow between your device and the web server is disrupted while attempting to view or load a webpage. In essence, it is a generic client error that occurs when the web server fails to comprehend the request.

To grasp this concept better, think of it as sending a letter without an address or any identifying information. The recipient wouldn’t know where it came from or who it’s intended for. Similarly, the 400 Bad Request error occurs when your browser fails to include sufficient information, leaving the server unable to process your request.

Causes of 400 Bad Request Errors

The 400 Bad Request error can stem from various underlying causes, and while it isn’t specific to any particular browser or operating system, the solutions may slightly differ.

1. Incorrect Links/URL

This error can manifest when an invalid URL is entered, often due to the presence of illegal characters in the URL string or a malformed link. Sometimes, users inadvertently send false request routing information through URLs, triggering problems, especially on web servers designed to scrutinize custom HTTP headers.

2. Browser Cache Issue

Browser caching, while improving loading times, can lead to server errors like the 400 Bad Request error if it accumulates too much data. This may result from damaged files in your browser cache or outdated/corrupted browser cookies.

3. DNS Cache Issue

When the DNS data on your computer becomes out of sync with the records on DNS servers, the 400 Bad Request error can surface. DNS cache stores domain-to-IP mappings locally on your computer, akin to how the browser cache stores web content.

4. File Size Too Large

Uploading files, such as images, videos, or documents, that exceed the server’s size limit can trigger an HTTP 400 error. Server configurations or acceptable file sizes may vary, but surpassing these limits can render your web page or content inaccessible.

Different Types of 400 Bad Request Errors

1. 402 Payment Required

The HTTP 402 Payment Required status code doesn’t have a specific meaning yet but was initially conceived for digital cash or micro-payment systems. It appears when a client attempts to access content they haven’t paid for.

2. 403 Forbidden

A 403 Forbidden error implies that your server is operational, but you may lack permission to access parts or all of your website. This often results from issues with your WordPress site’s file permissions or its .htaccess file.

3. 404 Not Found

The 404 error arises when a requested file or page cannot be located on the hosting server. It automatically sends the user an “404 Not Found” error message.

4. 408 Request Timeout

The 408 request timeout error materializes when a client’s request to the server goes unacknowledged within the allotted time frame, signifying that the client is taking too long to establish a secure connection.

How to Fix the 400 Bad Request Error in WordPress

1. Refresh the Page

The instinctive response when a website fails to load is hitting the refresh button. A forced refresh prompts your browser to bypass cached copies and request a fresh one from the server. Clearing your cache often resolves common issues, including the 400 Bad Request error.

  • Chrome on Windows: Ctrl + F5
  • Chrome on Mac: Command + Shift + R
  • Firefox on Windows: Ctrl + F5
  • Firefox on Mac: Command + Shift + R
  • Safari: Command + Option + R
  • Microsoft Edge: Ctrl + F5

2. Check the URL

Typographical errors or incorrectly formatted URLs can cause the 400 error. Ensure the domain name and page are correctly spelled out and separated by forward slashes. Verify that special characters in the URL are encoded correctly and compliant with URL standards.

3. Clear Browser Cache and Cookies

Corrupted files stored on your computer for a specific website can lead to a 400 Bad Request error. Deleting cookies and cache from your browser’s history can remedy this issue. The process varies by browser, but ensure that the entire history is cleared to prevent corrupted files from affecting other websites.

4. Clear DNS Cache

If clearing your browser cache doesn’t resolve the issue, flushing your local DNS cache may help. On Windows, open Command Prompt and enter: ipconfig /flushdns. This command should confirm that the DNS cache has been successfully cleared.

5. Deactivate Browser Extensions

Newly installed browser extensions or plugins can trigger the 400 Bad Request error. Deactivate or disable these extensions to determine if they are causing the issue.

6. Reduce Uploaded File Size

If you encounter an HTTP 400 bad request error while uploading files, it likely results from exceeding the file size limit set by your server. Ensure your files adhere to the size limits, and if necessary, compress or resize them before uploading.


Encountering a “400 Bad Request” error on your WordPress website is a common occurrence, but it need not be a cause for panic. In most cases, resolving the issue is as simple as clearing your browser cache or refreshing the page. However, persistent errors may indicate more significant website problems. If you require assistance with troubleshooting or maintaining your WordPress site, our expert team is here to help. Our Emergency WordPress Support services are available, even if you are not a Pronto client, to swiftly address your website’s issues for a one-time fee. Contact us today to learn more about our services and how we can support your online goals.

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