101 Switching Protocols
1xx Informational
RFC 9110
The server agreed to change the rules of the conversation.
What 101 Switching Protocols means {#what}
Sent when the server accepts a protocol upgrade request from the client. In practice, you see this almost exclusively during a WebSocket handshake — the connection starts as HTTP and upgrades to the WebSocket protocol.
When you’ll see a 101 {#when}
- Establishing a WebSocket connection (
Upgrade: websocket) - HTTP/1.1 to HTTP/2 upgrade in specific configurations