HTTP Response 412 - can you include content? <p>I am building a RESTful data store and leveraging Conditional GET and PUT. During a conditional PUT the client can include the Etag from a previous GET on the resource and if the current representation doesn't match the server will return the HTTP status code of 412 (Precondition Failed). Note this is an Atom based server/protocol.</p> <p>My question is, when I return the 412 status can I also include the new representation of the resource or must the user issue a new GET? The HTTP spec doesn't seem to say yes or no and neither does the Atom spec (although their example shows an empty entity body on the response). It seems pretty wasteful not to return the new representation and make the client specifically GET it. Thoughts?</p>