How to Fix a 400 Bad Request Error (2024)

The 400 Bad Request error is an HTTP status code that means the request you sent to the website server, often something simple like a request to load a web page, was somehow incorrect or corrupted and the server couldn't understand it.

How to Fix the 400 Bad Request Error

1. Check for errors in the URL. The most common reason for a 400 Bad Request error is because the URL was typed wrong or the link that was clicked on points to a malformed URL with a specific kind of mistake in it, like a syntax problem.

   This is most likely the problem. Specifically, check for extra, typically non-allowed, characters in the URL like a percentage character. While there are perfectly valid uses for something like a % character, you won't often find one in a standard URL.

2. Clear your browser's cookies, especially if you're getting a Bad Request error with a Google service. Many sites report a 400 error when a cookie it's reading is corrupt or too old.

3. Clear your browser's cache. A cached but corrupt copy of the web page you're trying to access could be the root of the problem that's displaying the 400 error. Clearing your cache is unlikely the fix for the majority of 400 bad request issues, but it's quick and easy and worth trying.

4. Clear your DNS cache, which should fix the 400 Bad Request error if it's being caused by outdated DNS records that your computer is storing. Do this in Windows by executing this command from a Command Prompt window:
   

    ipconfig/flushdns

   This is not the same as clearing your browser's cache.

5. Troubleshooting this as a 504 Gateway Timeout error instead, even though the problem is being reported as a 400 Bad Request.

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   In some relatively rare situations, two servers may take too long to communicate (a gateway timeout issue) but will incorrectly, or at least unconstructively, report the problem to you as a 400 Bad Request.

6. If you're uploading a file to the website when you see the error, chances are the 400 Bad Request error is due to the file being too large, and so the server rejects it.

   If the site permits it, compress the file to a ZIP file and then upload that instead.

7. If the 400 error is happening on nearly every website you visit, the problem most likely lies with your computer or internet connection. Choose an internet speed test to run, and then check with yourISP to make sure everything is configured correctly.

8. Contact the website directly that hosts the page. It's possible that the 400 Bad Request error actually isn't anything wrong on your end but is instead something they need to fix, in which case letting them know about it would be very helpful.

   Most sites have social network contacts and sometimes even telephone numbers and email addresses.

   If an entire site is down with a 400 Bad Request error, searching social media for #websitedownis often helpful,like #facebookdown or #gmaildown. It certainly won't contribute anything to fixing the issue, but if the site is down for everyone, at least you'll know you're not alone!

9. If nothing above has worked, and you're sure the problem isn't with your computer, you're left with just checking back later. Since the problem isn't yours to fix, revisit the page or site regularly until it's back up.

More Ways You Might See a 400 Error

Windows Update can report HTTP 400 errors but they display as error code 0x80244016 or with the message WU_E_PT_HTTP_STATUS_BAD_REQUEST.

A 400 error that's reported for a link within a Microsoft Office application will often appear as a The remote server returned an error: (400) Bad Request. message within a small pop-up window.

Web servers running Microsoft IIS often give more specific information about the cause of a 400 Bad Request error by suffixing a number after the400,as inHTTP Error 400.1 - Bad Request, which meansInvalid Destination Header.

Here's a complete list: