417 Expectation Failed

The HTTP 417 Expectation Failed client error response status code indicates that the expectation given in the request's Expect header could not be met. After receiving a 417 response, a client should repeat the request without an Expect request header, including the file in the request body without waiting for a 100 response. See the Expect header documentation for more details.

Status

417 Expectation Failed

Examples

Expectations unsupported

The following PUT request sends information about an intended file upload to a server. The client uses an Expect: 100-continue header and no request body to avoid sending data over the network that may result in an error such as 405, 401, or 403 response:

PUT /videos HTTP/1.1
Host: uploads.example.com
Content-Type: video/h264
Content-Length: 1234567890987
Expect: 100-continue

In this example server implementation, expectations are not supported and the presence of an Expect header with any value results in 417 responses:

HTTP/1.1 417 Expectation Failed
Date: 2024年6月28日 11:40:58 GMT

The client responds by making a request without expectations and with the content in the request body:

PUT /videos HTTP/1.1
Host: uploads.example.com
Content-Type: video/h264
Content-Length: 1234567890987
[...]

Specifications

See also

• HTTP response status codes
• 100 Continue
• Expect