Articles/HTTP

HTTP 505 HTTP Version Not Supported — What It Means

What HTTP status code 505 HTTP Version Not Supported means, when servers return it, and how to handle it correctly.

Published September 26, 2026

HTTP 505 HTTP Version Not Supported — The server doesn't support the HTTP protocol version used in the request.

Key points

  • Rare in modern usage since virtually all servers support HTTP/1.1 at minimum
  • Could appear if a very old or malformed client sends an unusual HTTP version string
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