426 Upgrade Required
4xx Client Error
RFC 9110
This protocol version won't cut it — please upgrade.
What 426 Upgrade Required means {#what}
The server refuses to process the request with the current protocol but will if the client upgrades. The server must include an Upgrade header indicating what protocol is needed.
When you’ll see a 426 {#when}
- Server requiring HTTPS when HTTP was used
- WebSocket endpoint requiring the WS protocol upgrade