All you need to know about error 400!

400 Bad Request errors mean that the client made an incorrect or corrupt request, and so the server cannot understand it.  To understand the 400 error, it must be understood that it is a client-side error. An error message indicates that the request submitted by the client cannot be handled. There are very less chances that the error is caused by a problem in server.

What is error 400? Explained in simple terms.

In the same way as 404, this is a status code for the Hypertext Transfer Protocol. Interactions between clients and servers are ongoing. The server responds when you click a link. HTTP status codes are displayed by the server to let you know if your request was successful.

Very few times, the client may not be able to access a resource due to server-side or client-side issues.

Known as 5xx error codes, these errors occur on the server side. For example, 502 error, 503 error and 504 error.

Known as 4xx error codes, these errors occur on the server side. For example, 400 error- Bad request, 401 unauthorized, 403 Forbidden error and 404 error-Not found, 408 request timeout error.

The basic meaning of 400 bad request error is that you sent an incorrect request or a corrupted request to the website server, which the server was unable to understand. There are also other relatively common causes for the 400 Bad Request error, including typing or pasting in the wrong URL.

Causes of 400 bad request error:

In most cases, a 400 Bad Request error is caused by an issue on the client’s side. Though it’s not the single reason possible, it is one of the most common cause! Wait, there are few other reasons as well.

  • In some cases, a 400 error is caused by a wrongly spelled URL or one with unrecognizable characters.  
  • when trying to log in as the administrator, you might receive a 400 Bad Request error. This happens when the cookie containing your authentication details is invalid.
  • Trying to upload a large file may also result in the server returning an error message. In case, the server has a limit on the size of files, you may receive a 400 error.
  • Though There is negligible chance that a 400 error could be caused by technical difficulties with the server, one shouldn’t overlook them.

The 400 Bad Request error and web pages both appears inside the browser window of the internet.

Fixes of 400 error:

  • Ensure the URL does not contain any errors. Most 400 Bad Request errors result from mistyped URLs or links that point to malformed URLs with specific kinds of errors in them, like syntax errors. A 400 Bad Request error usually implies that you have this problem. Examine the URL for extra characters, such as percentages, that are typically not allowed. % is not a standard URL character, even though there are various uses for it.
  • Clear the cache in your browser. An older cached copy of the webpage you’re trying to access might contain a corrupt copy. This would raise the 400 error. Trying to clear your cache won’t resolve most 400 bad request issues, but it’s a quick and easy fix.
  • If a Google service gives you a Bad Request error, clear your browser’s cookies.  The 400 error is typically triggered by a corrupted cookie or an outdated cookie.
  • Frequently, when you see a 400 Bad Request error, you’re uploading a file too large, which causes the server to reject your request. Upload the compressed ZIP file, if permitted by the site.
  • Though not being a familiar fix; instead of thinking of it as a 400 Bad Request, try troubleshooting the problem as a 504 Gateway Timeout. A gateway timeout issue may occur in some rare cases, causing two servers to take too long to communicate (and return you a 400 Bad Request) without really explaining the cause.
  • Flushing DNS cache: Another reason you receive an HTTP 400 Bad Request is that your DNS lookup data is corrupt or out-of-date. Clearing your DNS cache will fix the problem. Data related to DNS is stored in your operating system, not in your browser. Therefore there are different methods for individual operating system to clear DNS cache stored in respective OS. In case of windows operating system, following command can be used to clear DNS cache:


write above command in command prompt of windows OS.

  • When you encounter the 400 error almost every time you visit a website, your computer or internet connection are likely the cause. Test your internet speed and check with your ISP to ensure things are configured correctly. Restart your computer, as well as any other related equipment, if necessary.
  • If none of the above hacks works for you then don’t lose hope, there is always a way around! Please contact the page’s host directly. Perhaps there is nothing wrong on your end, but instead something they need to fix. If this is the case, letting them know may be of great help. Contact information is usually available on most sites via social networks, or even by phone and email.

The conclusion:

Any operating system or browser can display the 400 Bad Request error. In 99% cases, it’s an issue caused on client-side not on the server-side. Corrupted browser files and cookies often lead to the error, as do incorrectly inserted URLs and large files. It shouldn’t be too difficult for anyone with a bit of technical knowledge to implement the above solutions. The solutions are designed keeping in mind the comprehensions of a tech-naïve.  Server-side errors are only the cause of the issue in rare cases. The best thing to do in such cases is to contact the hosting company.

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