417 Expectation Failed

417 Expectation Failed is returned when the server cannot meet the expectation given in an Expect request header. The most common use case is Expect: 100-continue, which allows a client to check whether the server will accept a large request body before actually sending it.

• Client sending Expect: 100-continue but server doesn't support it
• Proxy stripping or mishandling the Expect header
• Outdated HTTP client with incorrect expectation headers

• Remove the Expect: 100-continue header if the server doesn't support it
• Update your HTTP client or library to handle server responses correctly
• Use a direct connection if a proxy is mishandling the header