4xx Client Error

HTTP 417 Expectation Failed

The expectation given in the Expect header could not be met by the server. The server cannot meet the requirements indicated by the Expect request-header field.

Common Causes

  • Server doesn't support Expect: 100-continue
  • Proxy or gateway not forwarding the Expect header
  • Server unable to meet the stated expectation

How to Fix

  1. 1Remove the Expect header from your request
  2. 2Send the request body directly without waiting for 100 Continue
  3. 3Check if intermediary proxies support the Expect header

Example

HTTP 417 Expectation Failed
POST /upload HTTP/1.1
Expect: 100-continue

→ 417 Expectation Failed
→ Server does not support this expectation

Related Client Error Codes

400

Bad Request

401

Unauthorized

402

Payment Required

403

Forbidden

404

Not Found

405

Method Not Allowed

406

Not Acceptable

407

Proxy Authentication Required

408

Request Timeout

409

Conflict

410

Gone

411

Length Required

412

Precondition Failed

413

Content Too Large

414

URI Too Long

415

Unsupported Media Type

416

Range Not Satisfiable

418

I'm a Teapot

421

Misdirected Request

422

Unprocessable Content

423

Locked

424

Failed Dependency

425

Too Early

426

Upgrade Required

428

Precondition Required

429

Too Many Requests

431

Request Header Fields Too Large

451

Unavailable For Legal Reasons