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HTTP Status Codes in the Overview – Part 2
The HTTP status code provides information about how or where HTTP requests are handled. But what do codes like 404, 200, 500, or 403 really mean? This understandable overview with HTTP status code helps web developers and creatives.
HTTP Status Codes in the Overview – Part 1
What is an HTTP status code?
Certainly, one or the other has already Error 404 – Page not found Or Error 403 – Access not allowed seen on a website. The corresponding code does not advance by chance.
With this so-called server response, the return of an HTTP status code is also done. This, consisting of a three-digit number and a brief description, transmits whether everything has been delivered correctly. (HTTP status code 200) or whether, for example, there was an internal error (HTTP 500) there. The HTTP status code is therefore part of the response returned by the server, for example, when a page is called.
HTTP status codes and their meanings
Since a lot can happen on the way from the browser to the server, there are many of these HTTP status codes. During transmission, it can also happen that the errors are recorded in more or less detail. Such a machine is sometimes just a human being.
Frequent codes such as HTTP 404, HTTP 403, Or HTTP 500 are certainly familiar. But there are still many codes that need some explanation. Therefore, here is an overview with HTTP status codes, sorted by function or category of HTTP return.
Status codes 4xx
The status code refers to errors that have occurred. Also, the cause of HTTP 4xx may be the input or connection to the appropriate software that sends a request.
| status code | Description | Importance |
| 400 Bad Request | Invalid request | The request failed. The syntax may have been incorrect or incomplete. |
| 401 Unauthorized | Unauthorized | Without authentication, the request cannot be executed. This is the case, for example, with protected pages if the name and/or password are not specified correctly. |
| 402 Payment Required | Payment required | The HTTP status code 402 is reserved for future HTTP protocols and represents a required payment. |
| 403 Forbidden | Prohibited | Access has been banned. Authentication could not be performed or acknowledged. |
| 404 Not Found | Not found | The page or resource could not be found. The HTTP status code 404 can also be used to reject requests for no further reason. |
| 405 Method Not Allowed | Method not allowed | The method by which the submission is submitted is not allowed. For example, we can set requests to be transmitted only with HTTP. Valid transmission methods are listed under “Allow” in the header. |
| 406 Not Acceptable | Unacceptable | The requested file is not available in the desired form. For example, a non-valid or incorrect “content-type” was specified. |
| 407 Proxy Authentication Required | Authentication required by proxy | Authentication is required. However, this must be done by proxy. This distinguishes this status code from “HTTP 401”, for example. |
| 408 Request Timeout | Request timed out | The request appears to have taken too long and exceeded the time specified by the server. This can be the case, for example, when uploading larger files or when running very complex scripts. |
| 409 Conflict | Conflict occurred | There has been a conflict with the request. A resource may have been modified in the meantime (for example, by the PUT method) so that it can no longer continue at this point. |
| 410 Gone | Disappeared | The file no longer exists on the server or has been permanently removed. There is no forwarding target. |
| 411 Length Required | Length required | Unable to process the request without “Content-Length” in the header. |
| 412 Precondition Failed | Precondition not met | An important precondition was not met when the server was asked. For example, this can be an “if-match” in the header. |
| 413 Request Entity Too Large | Request too large | The request to the server is so large that it cannot be processed. For example, the HTTP status code 413 can occur with larger uploads of files. |
| 414 URI Too Long | Address too long | The URL in the request is too long. Possible causes can be found, for example, in infinite loops from redirects. |
| 415 Unsupported Media Type | Unsupported media type | The request sends with an unsupported and invalid media or MIME type. |
| 416 Requested range not satisfiable | Area of the request cannot be fulfilled | A requested part of a specific resource may be invalid or currently not available to the server. |
| 417 Expectation Failed | Expectation not met | The expectation of the request could not be met. For example, you may encounter “Expect” in the header on proxy servers. |
| 418 I’m a teapot | April Fool’s joke | HTTP 418 is an April Fool’s joke by the IETF and represents a “protocol for coffee cooking” – the so-called “Hyper Text Coffee Pot Control Protocol”. |
| 420 Policy Not Fulfilled | Condition not sufficiently met | A code suggested by the W3C to express that a particular condition is not met. |
| 421 Misdirected Request | Request misdirected | HTTP status code 421 informs that a request has been sent to a server that is unable to respond to it. The status code was introduced to HTTP/2. |
| 422 Unprocessable Entity | No processing possible | If a request was still possible due to HTTP 400 or HTTP 415, the actual processing could not be done, for example, due to (programming) language errors. |
| 423 Locked | Locked | The requested resource is locked and inaccessible. |
| 424 Failed Dependency | Dependency not fulfilled | The request could not be made because the success of a previous request could not be fulfilled. |
| 426 Upgrade Required | Update required | The server prompts you to retry the request with a different protocol. You may want to switch to HTTP with Transport Layer Security. |
| 428 Precondition Required | Precondition required | Not all the preconditions required for the request could be met. This status code is intended to avoid problems caused by so-called race situations. |
| 429 Too Many Requests | Too many requests | Too many requests have been asked in a short period of time. Therefore, the edit is canceled. |
| 431 Request Header Fields Too Large | Head area is too long | The maximum length in one or more fields in the header has been exceeded. Therefore, the request cannot be processed. |
| 444 No Response | No answer | The server cannot return information. The connection is closed. |
| 451 Unavailable For Legal Reasons | not available for legal reasons | Certain content is not available for legal reasons. This may be the case, for example, due to slanderous copyrights or country restrictions. |
Status codes 5xx
If an HTTP status code with 5 appears at the beginning, therefore it is most likely an error on the part of the server.
| status code | Description | Importance |
| 500 Internal Server Error | Internal server error | The server has detected an internal error and is, therefore, unable to process the request. Scripting languages such as PHP can also trigger “HTTP 500”. |
| 501 Not Implemented | Not implemented | The server does not have the ability to process the request accordingly. An unrecognized or supported HTTP method may result in this error code. |
| 502 Bad Gateway | Poor portal | The server cannot make the request (in its gateway or proxy function) because it received an invalid response. |
| 503 Service Unavailable | Service not available | The server is currently unavailable. This can be the case, for example, in case of overload or maintenance. |
| 504 Gateway Timeout | Timeout at the portal | Within a certain amount of time, the server (in the role of gateway or proxy) could not receive a response. Therefore, the processing is aborted. |
| 505 HTTP Version not supported | HTTP version is not supported | The HTTP version used is not supported by the server. The processing is rejected. |
| 506 Variant Also Negotiates | Circular reference discovered | The request has a circular reference. Therefore, editing will not continue. |
| 507 Insufficient Storage | Insufficient storage space | There is insufficient disk space on the server. Therefore, the request is not processed. |
| 508 Loop Detected | Endless loop detected | Execution of the request is stopped because execution would end in an infinite loop. |
| 509 Bandwidth Limit Exceeded | Limitation of bandwidth achieved | The bandwidth available or set by the server has been reached. Therefore, the processing is aborted. |
| 510 Not Extended | Lack of information | Important information is missing from the request. Therefore, no further processing takes place at this point. |
| 511 Network Authentication Required | Network authentication required | Authentication is required before the request can be processed. |
Status Code Checker
A number of HTTP status code checkers are available to check whether pages are provided with HTTP dissenting status codes, for example, and that website redirects work as planned. With these online tools, we can determine if an unwanted “redirect” has not been hidden somewhere.
In Chrome Web Store for example, “Redirect Path”. With this Extension forwarding scan on pages. The HTTP status codes 301, 302, 404, and 500 are determined.
With the HTTP Status Codes Checker from httpstatus.io, which can check multiple addresses at once. You can download The result of the analysis directly as a CSV file.
Also, the status Code Checker comes with multiple addresses. Here, the result is optionally available for download as an Excel file.
HTTP Status Codes in the Overview – Part 1
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