428: Precondition Required

HTTP Status Code 428 indicates that a precondition required for the request is not met. This status code is part of the Client Error class and is used in situations where a conditional request was made, but the server cannot fulfill it due to the specified precondition being absent or false. Typically, this status code is employed in contexts involving conditional requests where the client expects a specific condition to be satisfied before proceeding with the operation. For example, when a client attempts to update a resource and includes a conditional header such as If-Match or If-None-Match, the server can respond with HTTP Status Code 428 if it finds that the precondition is not fulfilled, signaling to the client that it needs to address the issue before the request can be successfully processed. This code is particularly useful in ensuring that clients do not make unnecessary modifications to resources when certain conditions are not met, thereby promoting more efficient interactions between clients and servers.