HTTP Status Codes
Understanding the meaning of different HTTP response codes is crucial for effective monitoring. Here is a comprehensive list of common status codes.
1xx: Informational
Request received, continuing process.
The server has received the request headers and the client should proceed to send the request body.
The requester has asked the server to switch protocols and the server has agreed to do so.
A WebDAV request may contain many sub-requests involving file operations.
Used to return some response headers before final HTTP message.
2xx: Success
The action was successfully received, understood, and accepted.
Standard response for successful HTTP requests.
The request has been fulfilled, resulting in the creation of a new resource.
The request has been accepted for processing, but the processing has not been completed.
The server is a transforming proxy (e.g. a Web accelerator) that received a 200 OK from its origin, but is returning a modified version of the origin's response.
The server successfully processed the request and is not returning any content.
The server successfully processed the request, but is not returning any content. Unlike a 204 response, this response requires that the requester reset the document view.
The server is delivering only part of the resource (byte serving) due to a range header sent by the client.
3xx: Redirection
Further action must be taken in order to complete the request.
Indicates multiple options for the resource from which the client may choose.
This and all future requests should be directed to the given URI.
Tells the client to look at (browse to) another URL. 302 has been superseded by 303 and 307.
The response to the request can be found under another URI using the GET method.
Indicates that the resource has not been modified since the version specified by the request headers If-Modified-Since or If-None-Match.
In this case, the request should be repeated with another URI; however, future requests should still use the original URI.
The request and all future requests should be repeated using another URI.
4xx: Client Error
The request contains bad syntax or cannot be fulfilled.
The server cannot or will not process the request due to an apparent client error (e.g., malformed request syntax).
Similar to 403 Forbidden, but specifically for use when authentication is required and has failed or has not yet been provided.
The request was valid, but the server is refusing action. The user might not have the necessary permissions for a resource.
The requested resource could not be found but may be available in the future.
A request method is not supported for the requested resource (e.g. a GET request on a form that requires data to be presented via POST).
The server timed out waiting for the request.
Indicates that the request could not be processed because of conflict in the request, such as an edit conflict.
Indicates that the resource requested is no longer available and will not be available again.
The user has sent too many requests in a given amount of time (rate limiting).
5xx: Server Error
The server failed to fulfill an apparently valid request.
A generic error message, given when an unexpected condition was encountered and no more specific message is suitable.
The server either does not recognize the request method, or it lacks the ability to fulfill the request.
The server was acting as a gateway or proxy and received an invalid response from the upstream server.
The server is currently unavailable (because it is overloaded or down for maintenance).
The server was acting as a gateway or proxy and did not receive a timely response from the upstream server.
Cloudflare utilized as a catch-all response for when the origin server returns something unexpected.
The origin server has refused the connection from Cloudflare.
Cloudflare could not contact the origin server.
Cloudflare could not reach the origin server; for example, if the DNS records for the origin server are incorrect.