101
Informational
101 Switching Protocols
Server confirms protocol switch requested by the client via the Upgrade header — typically to WebSocket or HTTP/2.
Definition (RFC 9110)
HTTP status code 101 101 Switching Protocols is defined in RFC 9110 (HTTP Semantics), Section 15.2.2 — the current authoritative specification for HTTP semantics, published June 2022, which obsoletes the older RFC 7231 and RFC 2616.
Description
The 101 Switching Protocols response indicates that the server accepts the client's request to switch protocols. This is commonly seen during WebSocket upgrades.
The server sends this response with an Upgrade header indicating the protocol it's switching to.
Common Causes
WebSocket handshake (Upgrade: websocket)
HTTP/1.1 to HTTP/2 upgrade (Upgrade: h2c)
Client explicitly requested protocol switch
How to Fix
This is a normal status code, not an error. If you didn't expect protocol switching, inspect your client code (JavaScript WebSocket, HTTP/2 client).
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