416
4xx Client ErrorRange Not Satisfiable
The requested range can't be fulfilled for the resource.
416 Range Not Satisfiable means the Range header asked for bytes the resource doesn't have, like a range that starts past the end of the file. It usually appears when a download resumes against a file that changed size in the meantime, or when range math is built from a stale Content-Length.
What 416 looks like on the wire
GET /videos/intro.mp4 HTTP/1.1 Host: cdn.example.com Range: bytes=99999999- HTTP/1.1 416 Range Not Satisfiable Content-Range: bytes */31457280
About 4xx Client Error
The request has a problem the client needs to fix, like a bad URL, missing auth, or invalid input.
How to fix 416 Range Not Satisfiable
- Restart the download from scratch - the partial file no longer matches the source.
- Use If-Range on resumed downloads so a changed file falls back to a full 200.
- Double-check hand-built Range headers: byte ranges are zero-indexed and inclusive.
Where it's defined
416 Range Not Satisfiable is defined in RFC 9110 §15.5.17. MDN's 416 reference covers browser behavior and examples.