What are Website Error & Status Codes?
Regardless of the provisions you make and the safeguards you put in place, websites, even the well known sites like Facebook and Amazon, will experience issues from time to time.
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In some cases, errors may occur because due to a slow loading website page but website faults, known as HTTP error codes, are messages from the website's server that let you know there was an error or issue.
Knowing and understanding HTTP error codes are crucial if you are a website owner or developer, so when they appear you know how to diagnose and resolve the issue.
The items detailed below show the errors which can occur with a website, along with the corresponding codes which are shown and what they mean.
HTTP Error Classes & Codes
100 response codes are informational and indicate that the request which was made by the web browser is continuing.
100: Continue
This code highlights that the server has received the web browser’s request headers and is now ready for the request body to be sent as well. This prevents the browser from sending a body request if the request headers have been rejected and makes the process of requesting a website more efficient.
101: Switching Protocols
The web server has complied with the web browser's request to change the protocols.
103: Early Hints
This code returns the response headers before the remaining response of the server is ready.
A 200 code range of responses simply means that everything is working exactly as it should.
200: Everything is OK
This code indicates that a website has been processed and provided exactly what it expected.
201: Created
Highlights that a new resource has been created after the server has completed the web browser's request.
202: Accepted
This code shows that that the request made by the web browser has been accepted but is still processing.
203: Non-Authoritative Information
A proxy may be in use and has modified the response before sending it to the web browser, once a 200 status code or 'Everything Is OK', has been received from the original server.
204: No Content
A 204 code means that even though the server has successfully processed the request, no content will be returned to the web browser.
205: Reset Content
Similar to a 204 status code with no content being returned but requires the web browser to reset the document view.
206: Partial Content
If the web browser uses 'Range Headers', this status code instructs the web browser to resume any downloads which have been paused, or to split up a download.
Provided as part of a redirection when another request has been made for a different website or resource. For example, when a resource which has been requested by a web browser has been moved to a different page or domain.
300: Multiple Choices
This response code means that the web browser needs to choose between multiple resources, occurring when there are multiple file type extensions to choose from.
301: The requested resource has been moved permanently
This is a permanent redirect and indicates when a resource or website page has been moved permanently and replaced by a different resource, link, website page or domain.
302: The requested resource has moved, but was found
This is a temporary redirect which is provided when a resource has been found, just not where it was originally expected.
303: See Other
When returned, a 303 response code recognises that the web browser has requested a resource from the web server using the POST, PUT or DELETE 'http', method. In return, a required request using the GET 'http', method using a different URL is needed.
304: The requested resource has not been modified since the last time you accessed it
This response code informs the web browser that the information stored in it's cache has not been changed.
307: Temporary Redirect
The same has a 302 response code, except that it does not allow the 'http', request to change.
308: Permanent Redirect
The same has a 301 response code, except that it does not allow the 'http', request to change.
The 400 range of response codes indicate that there was a problem with the request made by a client or web browser.
400: Bad Request
The web server is unable to provide a response because of an error with the request from the user, or the web browser which they are using.
401: Unauthorised
Showing as 'Unauthorised', or 'Authorisation Required', this response code is returned by the web server when the required authentication credentials are not provided.
402: Payment Required
Originally created to be used as part of a digital cash system, it is now used by various platforms to indicate that a process cannot be completed due to a lack of funds.
403: Access To That Resource Is Forbidden
When a user attempts to view a web page or resource without the correct permissions, this response code indicates that a password or further credentials are required.
404: The Requested Resource Was Not Found
A common response code or error, this simply highlights that the requested resource, web page or domain cannot be found.
405: Method Not Allowed
This response code is generated by the web server when it supports the request which was made, but not supported, by the website page or resource.
406: Not Acceptable Response
A 406 code shows that the web server is only capable of generating content, which is not acceptable, in relation to the accept headers sent in the original request.
407: Proxy Authentication Required
This indicates that the web browser needs to authenticate a request with a proxy server, before being allowed to continue.
408: The server timed out waiting for the rest of the request from the browser
This error occurs when a web server doesn't receive the full request or packets of data, originally sent by a web browser.
409: Conflict
This response code shows that the web server was unable to process a request made by a web browser, due to a conflict with the requested resource.
410: The requested resource is gone and won’t be coming back
Similar to a 404 response code, 'Not Found', instead highlighting that it was expected and permanent.
411: Length Required
This response code indicates that a length is required as part of the request, which was not provided.
412: Precondition Failed
The server was unable to process certain specifications, which were included within the request headers of the web browser.
413: Payload Too Large
The server is not willing or unable to process a request, as the request is too large.
414: URI Too Long
An encoded query string, normally the result of a GET 'http', request, is too large for the web server to process.
415: Unsupported Media Type
This response code indicates that the web server does not recognise or support a media type which has been used.
416: Range Not Satisfiable
The web server is unable to return a portion of a resource, which was requested.
417: Expectation Failed
This error code is shown when the web server is not able to fulfil the requirements, which are detailed in the header field of the original request.
418: I'm A Teapot
Originally an April Fool's joke from 1998, the response code is returned by teapots which receive a request to make coffee.
422: Unable To Process Entity
The web server is unable to process a request due to semantic errors.
425: Too Early
This error code highlights that the web server is not able to process a request, because it may be replayed.
426: Upgrade Required
This response code requires that the client changes to a different protocol, because of the original request's header field.
428: Precondition Required
Before processing the request, this error code indicates that the web server has a set of conditions that need to be specified.
429: Too Many Requests
Normally generated from bots or scripts attempting to access a website, this response code highlights that the web server has received too many requests within a specific amount of time.
431: Request Header Fields Too Large
Indicates that there may be an issue with the header fields being too large for the web server to process.
451: Unavailable for Legal Reasons
Access is prohibited to a set of resources on a web server due to legal reasons.
499: Client Closed Request
This response code is generated from NGINX, pronounced 'Engine X', a high performance, http web server, reverse proxy and load balancer, when the web server request is cancelled while being processed.
Response codes that show the 500 range, normally specify that there is an issue with the web server.
When visiting a website, the browser makes a request to the server where the website is located. If there is an issue with the server, not the website, a 500 response code is returned with the following:
500: There was an error on the server and the request could not be completed
This is generic code that simply means there was an error on the server, which resulted in the request not being delivered.
501: Not Implemented
This response code shows that the web server does not support the functionality required for access or recognise the request method.
502: Bad Gateway
This response code shows that while the server was acting as a gateway or proxy, it received an invalid response from the upstream server.
503: The server is unavailable to handle this request right now
This indicates that the web server is operating properly but it can't handle a request at the moment. Since it's a generic error message, it's difficult to pinpoint the exact cause.
504: The server, acting as a gateway, timed out waiting for another server to respond
This response code highlights that there are two servers involved in processing a request, with the first server timing out while waiting for the second server to respond.
508: Resource Limit Is Reached
The limits which are set for the resources being used by the server, which are used to host the website, have been reached.
511: Network Authentication Required
This status code is sent by a network, when the website or web server requires further authentication or security.
521: Web Server Is Down
This is a specific response code which is used by Cloudflare, a content delivery network and DDoS mitigation service. The error highlights that the web browser was able to connect with the Cloudflare service but unable to connect with the original web server.
525: SSL Handshake Failed
Again, this is a specific code which is used by Cloudflare and indicates that the secure, SSL handshake which is required to establish a secure connection between Cloudflare and the original server has failed.
In Summary
Website status codes are numbers sent by a web server to the browser, in response to an online request. They tell you if a website page has loaded normally, been redirected, or failed because of a client or server problem.
Related Information
To understand and learn more, the following information and related resources are available within our Knowledge Base.
