412 Precondition Failed

The HTTP 412 Precondition Failed client error response code indicates that access to the target resource has been denied. This happens with conditional requests on methods other than GET or HEAD when the condition defined by the If-Unmodified-Since or If-None-Match headers is not fulfilled. In that case, the request, usually an upload or a modification of a resource, cannot be made and this error response is sent back.

Status

412 Precondition Failed

Specifications

Specification	Title
RFC 7232, section 4.2: 412 Precondition Failed	Hypertext Transfer Protocol (HTTP/1.1): Conditional Requests

Browser compatibility

See also

• 304
• If-Unmodified-Since
• If-None-Match