Status Code 400

A HyperText Transfer Protocol Bad Request 400 indicates a client error. When the client sends an invalid request to the server, the server issues an HTTP status code 400. A high number of 400 errors can negatively affect the usability of websites, and is usually caused by an incorrectly entered URL. [1]


The 400 (Bad Request) status code indicates that the server cannot or will not process the request due to something that is perceived to be a client error.[2]  In response to an invalid request, the server should issue the exact 4xx code in the case of an unsuccessful request.

Common Causes

A 400 Bad Request error is usually the result of entering the wrong URL in the browser address window, or by making mistakes in a link's address when linking from page to page. 

How to fix 400 Errors

  • Check that the entered URL is correct: The URL and link syntax should be correct, and the target URL should exist. You can use Ryte's Website Success to crawl a website and ensure all link targets are a 200 Success code. 
  • Clear your DNS Cache: The errors might be being displayed as your computer is storing outdated DNS records. Execute ipconfig/flushdns from a Command Prompt to do this. 
  • Clear your browser cache: Another reason could be that your cached version of the page is still suffering from the 400 status code error. In your browser's History, you can clear your cache that would resolve this problem. 
  • Clear your browser's cookies: While you're there in your browser's History, you could also clear your cookies. This is the best practice when you're getting a Bad Request error on a Google site or service. 

List of all 4xx status codes

Errors with the status code 4xx are listed below:

* 400 bad request: All errors with the status code 4xx indicate an invalid request from a client to a server.

* 401 unauthorized: This request to the server requires the client to authorize. This is usually done by logging in. If a user still wants to access the password-protected resource, the status code 401 (unauthorized) appears with a note on what to do.

* 402 payment required: This status code is for future use. It will indicate that you have to pay a fee in order to view the content, and that it will only be visible after payment.

* 403 forbidden: Access is denied even with valid login data. This can happen for example when a site is requested with HTTP, but is configured with HTTPS.

* 404 not found: One of the most frequently displayed status codes is the 404-error. It is used to indicate that a requested link does not exist. If the error page displays a different HTTP status code to 404, this results in a soft 404 error.

* 405 method not allowed: The request was made using the wrong request method. The required method, such as GET or POST is explained by the response within the error code.

* 406 not acceptable: In this case, the format requested by the client cannot be issued by the server. The content type is available in the server response.

* 407 proxy authentication required: Similar to status code 401, the server requests authentication by the client, in this case in relation to the proxy server being used.

* 405 request time-out: This code is displayed if the client could not send a complete request in the time period defined by the server.

* 409 conflict: This request by the client is rejected by the server because it was submitted under a false assumption. This status code may get output if the resource has changed.

* 410 gone: If the user receives this status code, it means that the resource is no longer available and/or has been deleted.

* 411 length required: If this code appears, the content length needs to be specified in the header to process the client request.

* 412 precondition failed: In this case, the prerequisite has been defined in the request, which does not apply. (for example, an if match)

* 413 request entity too large: This indicates that the request was too big to be processed by the server in question. The server response may include the instruction to try again later.

* 414 request-URI too long: The server cannot respond because the URI is too long. This is usually caused by too many redirects.

* 415 unsupported media type: This request cannot be answered because the media type is not available.

* 416 request range not satisfiable: This error code indicates that a portion of the requested resource is no longer available or invalid.

* 417 expectation failed: This code will be output if the “expect” field of the header specifies a particular request that the server that cannot fulfill.

* 422 unprocessable entity: This code indicates that the request cannot be processed. This could be caused by semantic errors, but not media type errors as is the case with 415.

* 423 locked: The requested resource is temporarily locked and not accessible.

* 424 failed dependency: If this status code is issued, two requests were made. The second request depended on the first, but was unsuccessful.

* 426 upgrade required: In order for the server to handle this request, the client must use TLS 1.0.

* 428 precondition required: Preconditions must be fulfilled In order to execute this request successfully.

* 429 too many requests: This code is issued by the server if it received too many requests from a client within a certain period of time. This may occur, for example, if an SEO tool queries too many keywords on Google within a short period of time.

* 431 request header fields too large: If the length of the header field or the entire header has been exceeded, this status code appears.


  1. RFC2616-sec10 Accessed on June 12, 2019
  2. RFC 2731 Section 6.5.1. 400 Bad Request Accessed on June 12, 2019

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