4XX Response Codes

Introduction

HTTP Status codes are basically the conversion between the web browser and the website's server. In most cases, you as a user won't be able to see the HTTP status codes unless and until there is an issue. In case of issue HTTP status codes are used as a way of communicating errors to the user.

Error messages or we can say HTTP codes are displayed when your internet browser is unable to reach the page requested by a user.

What is a 4xx Response?

This group of HTTP status codes indicates that the request for the resource contains bad syntax or cannot be filled for some other reason, presumably by the fault of the client sending the request. Except when responding to a HEAD request, the server SHOULD include an explanation of the error situation and whether it is a temporary or permanent condition. These status codes are applicable to any request method.

What do 4xx Response Look Like?

4XX status codes are shown when the client requests a page that cannot be accessed. This is usually the result of a bad or broken link. These statuses are the most common requests an SEO will encounter – the 400, 403 and 404 errors. These errors simply mean that the resource is unavailable and unable to load. For instance, you may encounter 401 response code like this:

Guide to 4xx Response Codes-

There are a number of different 4xx server Responses, numbered with their own response codes so that the problem can be identified.

Some of the most common HTTP 4xx Response codes are listed below:

S no.	Response Code	Response Name	Description
1	400	Bad Request	The server cannot or is unable to process the request due to an apparent client error.
2	401	Unauthorized	It is to be specifically used when authentication is required and has failed or has not yet been provided.
3	402	Payment Required	This code is Reserved for Future Use. This code might be used as a part of some form of digital cash or micropayment scheme.
4	403	Forbidden	The request contained valid data and was understood by the server, but the server is refusing action.
5	404	Not Found	The requested resource cannot be found but may be available in the future.
6	405	Method Not Allowed	The requested method is not supported by the requested resource.
7	406	Not Acceptable	The requested resource is capable of generating only content not acceptable according to the Accept headers sent in the request.
8	407	Proxy Authentication Required	The client must first authenticate itself with the proxy.
9	408	Request Timeout	The server timed out waiting for the request.
10	409	Conflict	The request could not be processed because of the conflict in the current state of the resource.
11	410	Gone	The requested resource is no longer available and will not be available again.
12	411	Length Required	The request did not specify the length of its content, which is required by the requested resource.
13	412	Precondition Failed	The server does not meet one of the preconditions that the requester put on the request header fields.
14	413	Payload Too Large	The request is larger than the server is willing or able to process.
15	414	URI Too Long	The URI provided was too long for the server to process.
16	415	Unsupported Media Type	The request entity has a media type that the server or resource does not support.
17	416	Range Not Satisfiable	The client has asked for a portion of the file, but the server cannot supply that portion.
18	417	Expectation Failed	The server cannot meet the requirements of the Expect request-header field.
19	418	I'm a teapot	This HTTP status is used as an Easter egg on some websites, including Google.com.
20	421	Misdirected Request	The request was directed at a server that is not able to produce a response.
21	422	Unprocessable Entity	The request was well-formed but was unable to be followed due to semantic errors.
22	423	Locked	The resource that is being accessed is locked.
23	424	Failed Dependency	The request failed because it depended on another request and that request failed.
24	425	Too Early	The indicates that the server is unwilling to risk processing a request that might be replayed.
25	426	Upgrade Required	The client should switch to a different protocol such as TLS/1.0, given in the Upgrade header field.
26	428	Precondition Required	The origin server requires the request to be conditional.
27	429	Too Many Requests	The user has sent too many requests in a given amount of time.
28	431	Request Header Fields Too Large	The server is unwilling to process the request because either an individual header field or all the header fields collectively, are too large.
29	451	Unavailable For Legal Reasons	A server operator has received a legal demand to deny access to a resource or to a set of resources that includes the requested resource.

Unofficial Codes

S no.	Response Code	Response Name	Description
1	419	Page Expired (Laravel Framework)	Used by the Laravel Framework when a CSRF Token is missing or expired.
2	420	Method Failure (Spring Framework)	A deprecated response used by the Spring Framework when a method has failed.
3	420	Enhance Your Calm (Twitter)	Returned by version 1 of the Twitter Search and Trends API when the client is being rate limited; versions 1.1 and later use the 429 Too Many Requests response code instead.
4	430	Request Header Fields Too Large (Shopify)	Used by Shopify, instead of the 429 Too Many Requests response code, when too many URLs are requested within a certain time frame.
5	450	Blocked by Windows Parental Controls (Microsoft)	The Microsoft extension code indicated when Windows Parental Controls are turned on and are blocking access to the requested webpage.
6	498	Invalid Token (Esri)	Returned by ArcGIS for Server. Code 498 indicates an expired or otherwise invalid token.
7	499	Token Required (Esri)	Returned by ArcGIS for Server. Code 499 indicates that a token is required but was not submitted.

Internet Information Services

S no.	Response Code	Response Names	Description
1	440	Login Time-out	The client's session has expired and must log in again.
2	449	Retry With	The server cannot honour the request because the user has not provided the required information.
3	451	Redirect	Used in Exchange ActiveSync when either a more efficient server is available or the server cannot access the users' mailbox.

Nginx

S no.	Response Code	Response Name	Description
1	444	No Response	Used internally to instruct the server to return no information to the client and close the connection immediately.
2	494	Request header too large	Client sent too large request or too long header line.
3	495	SSL Certificate Error	An expansion of the 400 Bad Request response code, used when the client has provided an invalid client certificate.
4	496	SSL Certificate Required	An expansion of the 400 Bad Request response code, used when a client certificate is required but not provided.
5	497	HTTP Request to HTTPS Port	An expansion of the 400 Bad Request response code, used when the client has made a HTTP request to a port listening for HTTPS requests
6	499	Client Closed Request	Used when the client has closed the request before the server could send a response.

AWS Elastic Load Balancer

S no.	Response Code	Response Name	Description
1	460	NA	Client closed the connection with the load balancer before the idle timeout period elapsed.
2	463	NA	The load balancer received an X-Forwarded-For request header with more than 30 IP addresses.

Conclusion

Since user error is often what triggers a 4xx status code, we have consolidated a list of things you can do to remedy the situation if it happens to you. For all status codes listed above, if the listed solutions don't work, clear the cache and cookies to make sure those aren't causing the error.