417 Expectation Failed
When you encounter the 417 Expectation Failed error, it means that the server cannot meet the expectations specified by the client in the request’s “Expect” header.
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Introduction
In Action
Sample
Conclusion
Introduction
When you encounter the 417 Expectation Failed error, it means that the server cannot meet the expectations specified by the client in the request’s “Expect” header.
The client may have set certain conditions for the server to fulfill before processing the request, but the server is unable to meet those requirements, resulting in this error response.
In Action
When you receive the 417 Expectation Failed error message, it means that the client included specific conditions in the “Expect” header of the request, expecting a certain response from the server.
However, the server or the response chain doesn’t support these expectations, leading to the error. To resolve this, the client can try resending the request without the “Expect” header.
This status code is related to the informational response “100 Continue,” where the server evaluates the request details before deciding whether to proceed or reject the message body. If the server accepts the message body, it responds with “100 Continue,” but if it doesn’t support the expectations, it returns the “417 Expectation Failed” error.
Sample
In the example, when the client attempts to send a 10K PDF file, it includes specific expectations in the request header.
However, the server is unable to support these expectations and returns the 417 Expectation Failed error message. To fix this, the client can try resending the request without the expectation headers.
Request
PUT /docs HTTP/1.1
Host: www.example.com
Content-Type: applications/pdf
Content-Length: 10000
Expect: 100-continue
Response
HTTP/1.1 417 Expectation Failed
Content-Type: text/html
Content-Length: 155
< html>
< head>
< title>Expectations not supported< /title>
< /head>
< body>
< p>We don’t expect much, and neither should you.< /p>
< /body>
< /html>
Conclusion
The 417 Expectation Failed error code indicates that the server cannot meet the expectations set by the client in the request header.
This status is typically returned when the server does not support certain conditions specified by the client, and the client can resolve the issue by resending the request without the expectation headers.
