Expect HTTP request header indicates expectations that need to be met by the server to handle the request successfully.
Expect: 100-continue, the server responds with:
100(Continue) if the information from the request header is sufficient to cause immediate success
417(Expectation Failed) if the server cannot meet the expectation
or any other 4xx status otherwise.
For example, the server may reject a request if its
Content-Length is too large.
No common browsers send the
Expect header, but some other clients such as cURL do so by default.
|Header type||Request header|
|Forbidden header name||yes|