HTTP Status 400 Codes
Information about HTTP status codes 400 to 499, their meaning, and any related restrictions.
HTTP code 400 - Client Error
Description
An error situation occurred which seems to be caused by the client. Information about the error should be returned and displayed unless a HEAD request was performed.
The request cannot be processed due to a client error, such as malformed request.
Authentication is required but has not been provided. This is similar to 403, but is used when authentication is required and hasn't been provided.
The response will include a www-authenticate header containing authentication details.
Unused status code originally intended to be used as part of a payment system.
Google Developers API, Shopify, and Stripe use this.
The request is valid but is refused because the user does not have appropriate permissions, or because the action is not allowed. It is also used when a www-authenticate check fails.
The request should not be repeated.
The resource could not be found, but may be available in the future.
The resource is not acceptable according to the accept headers sent by the client.
The client must authenticate with the proxy.
The client did not complete the request within the server's timeout period.
A state conflict prevented the request being processed.
The resource has been removed and is no longer available. No subsequent requests should be made for the resource, and the resource should be removed from any search index.
No content-length was specified in the request and one is required.
The client supplied preconditions in the request header and these have not been met by the server.
The request payload is too large.
The requested URI is too long for the server. This is often the result of encoded data in a GET request.
The requested resource has a media type which the server is unable to support.
Requested Range Not Satisfiable
The client requested a range which the server is unable to serve. For example, it is beyond the end of the resource.
The client supplied an expect header that the server cannot fulfill.
A hilarious April Fool's joke.
Issued by Twitter Search and Twitter Trends version 1 when the client is rate limited. Subsequent versions use 429.
The server is unable to produce a response for the request.
The server does not want to process the request as it might be replayed.
The client should switch to the protocol provided in the upgrade header.
The server requires the request to be conditional so as to prevent an update being lost when a resource is modified.
The resource is rate-limited and the client has sent too many requests in the allotted time.
Request Header Fields Too Large
Issued by Shopify to indicate a rate-limit effect. This is used instead of 429.
Request Header Fields Too Large
Some request headers are too large for the server to support.
Blocked by Windows Parental Controls
Issued by Microsoft when Windows Parental Controls are turned on and a resource is blocked.
The server is unable to return the resource due to legal reasons.
Internal response that tells the server to close the connection and return no information.