417 Expectation Failed
The server cannot meet the requirement set in the request's Expect header.
What it means
HTTP 417 Expectation Failed means the request carried an Expect header — almost always Expect: 100-continue — and the server cannot satisfy that expectation. The client asked the server to confirm it would accept the body before sending it, and the server, or an intermediary, could not honour the handshake.
When it happens
It happens when a client sends Expect: 100-continue through a proxy or server that does not support it, breaking the continue handshake during an upload.
How to fix it
- Drop the Expect header so the client sends the body without waiting for a 100 Continue.
- Check whether a proxy between client and server is mishandling the Expect header.
- Update or reconfigure the server if it should support the expectation but does not.
SEO impact
None for normal pages. The Expect handshake relates to uploads, not to how crawlers fetch pages.
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Related codes
The server could not understand the request due to malformed syntax.
401 UnauthorizedAuthentication is required and has failed or not been provided.
402 Payment RequiredA largely reserved code intended for payment-gated access to a resource.
403 ForbiddenThe server understood the request but refuses to authorize it.
404 Not FoundThe server could not find the requested resource.
405 Method Not AllowedThe HTTP method used is not supported for the requested resource.
Related guides
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