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Introduction
HTTP Status Code 417-Expectation Failed is one of the classes of 4xx(Server Error) response code that indicates the request’s Expect header expectation could not be fulfilled.
General Understanding
When a server encounters an Expect header it doesn’t understand or support, it returns 417 Expectation Failed.
The Expect header can be used by a client to inform the server that it expects a certain response from the server.
The only uniform expectation (as far as I’m aware) is 100-continue.
This is how it appears:
| POST /foo/bar HTTP/1.1 Content-Type: application/gzip Content-Length: 12345678765 Expect: 100-continue … |
This request is for a huge file to be uploaded. The client informs the server that it wants a 100 Continue answer from the server first.
If a server supports this, it will initially respond with a 100 Continue answer, indicating that the request was understood, accepted, and most likely acceptable and that the client can proceed with the upload.
If the server does not support this functionality, it must respond with an error code of 417:
| HTTP/1.1 417 Expectation Failed Content-Type: text/plain We don’t support 100-continue |
A server should always return 417 if it encounters a different sort of expectation, such as a new future standard or a custom extension.
Status
| 417 Expectation Failed |
Possible Cause
One probable cause is that your server is expecting data in a specific format or encoding, which you did not supply. In rare cases, certain servers will reject the expect-continue flag if it is set to ON.
Possible Solutions
You can attempt one of two different workarounds.
If you’re using an XML Data type in your SQL Query and delivering the result to a remote server via a Web API Destination or SSIS REST API Task.
- Change your source SQL query to output nvarchar datatype instead of XML datatype for your XML data.
select CAST(myXmlColumn as nvarchar(max)) as myXmlColumn from myTable
2. If you’re not utilizing the XML data format and are still getting the 417 Expectation Failed problem, consider adding a Script Task before using any API (add the first step in your flow).
Edit the Microsoft SSIS Script Task by dragging it.
Add the following one line to the script’s Main method, shut it, and try running your package again to see if it helps.
| System.Net.ServicePointManager.Expect100Continue = false; |
Specifications
| Specification | Title |
| RFC 7231, section 6.5.14: 417 Expectation Failed | Hypertext Transfer Protocol (HTTP/1.1): Semantics and Content |
Related Articles
| HTTP Status Code 207 Multi-Status |
| HTTP Status Code 300-Multiple Choices |
| HTTP Status Code 302 Found |
| HTTP Status Code 204 – No Content |
FAQ
What does HTTP Status Code 417 mean?
HTTP Status Code 417-Expectation Failed is one of the classes of 4xx(Server Error) response code that indicates the request’s Expect header expectation could not be fulfilled.
What are the causes of HTTP Status Code Error 417?
One probable cause is that your server is expecting data in a specific format or encoding, which you did not supply. In rare cases, certain servers will reject the expect-continue flag if it is set to ON.
417 CODE REFERENCES
| Rails HTTP Status Symbol | :expectation_failed |
| Go HTTP Status Constant | http.StatusExpectationFailed |
| Symfony HTTP Status Constant | Response::HTTP_EXPECTATION_FAILED |
| Python2 HTTP Status Constant | httplib.EXPECTATION_FAILED |
| Python3+ HTTP Status Constant | http.client.EXPECTATION_FAILED |
| Python3.5+ HTTP Status Constant | http.HTTPStatus.EXPECTATION_FAILED |
Conclusion
That should cover all the bases when it comes to HTTP Status code 417-Expectation Failed issues. While there isn’t always much you can do when you get a 417 error, maybe some of these tips will come in handy the next time you get one.
I hope this article was able to help you with your doubts and queries related to the HTTP status code 417 Expectation Failed
Still, if there are any queries related to this topic, feel free to ask in the comment section, we would be happy to assist you. Thank you.
Saurabh Chalise