Range Not Satisfiable

Overview

416 Range Not Satisfiable means the byte range the client requested via the Range header lies outside the actual size of the resource. Asking for bytes at the 100 MB mark of a 5 MB file triggers it.

It commonly appears in resumable downloads or media streaming when the client has a stale idea of the file size. The server responds with Content-Range: bytes */<total> so the client learns the real size.

When it happens

• Requesting a start offset larger than the file size via Range
• Resuming a download where the stored size disagrees with the server
• Specifying multiple overlapping or invalid ranges

Request / Response example

GET /video.mp4 HTTP/1.1
Host: cdn.example.com
Range: bytes=99999999-100000000

HTTP/1.1 416 Range Not Satisfiable
Content-Range: bytes */5242880
Content-Type: text/plain

Requested range not satisfiable

In code

const size = fs.statSync(file).size;
const m = /bytes=(\d+)-(\d*)/.exec(req.headers.range || '');
const start = m ? Number(m[1]) : 0;
if (start >= size) {
  res.writeHead(416, { 'Content-Range': `bytes */${size}` });
  return res.end();
}

# Ask for the first 1024 bytes; a valid range yields 206, an out-of-bounds one 416
curl -r 0-1023 https://cdn.example.com/video.mp4 -o chunk.bin

Notes

• A valid partial request succeeds with 206 Partial Content; 416 only appears when the range itself is invalid.
• You can tell whether a server supports range requests from the Accept-Ranges: bytes header in its responses.

Related status codes

Related headers

Specification