1xx Informational

HTTP 101 Switching Protocols

The server is switching protocols as requested by the client via an Upgrade header. This is commonly used when upgrading an HTTP connection to WebSocket.

Common Causes

  • WebSocket connection upgrade request
  • HTTP/2 upgrade negotiation
  • Protocol switch requested via Upgrade header

How to Fix

  1. 1No fix needed — this is expected during protocol upgrades
  2. 2Ensure both client and server support the target protocol
  3. 3Verify the Upgrade header specifies a valid protocol

Example

HTTP 101 Switching Protocols
GET /chat HTTP/1.1
Upgrade: websocket
Connection: Upgrade

→ Server responds 101 Switching Protocols

Related Informational Codes

100

Continue

102

Processing

103

Early Hints