101 Switching Protocols

What This Error Means

The server is switching protocols as requested by the client.

The server understands and is willing to comply with the client's request to switch protocols.

Common Causes

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

How to Fix It (For Visitors)

• This is not an error - protocol upgrade in progress

How to Fix It (For Developers/Admins)

• Ensure proper WebSocket handshake implementation
• Handle protocol upgrades correctly

Code Examples

Here's how to return a 101 status code in various programming languages:

Python (Flask)

from flask import Flask, jsonify

app = Flask(__name__)

@app.route('/endpoint')
def endpoint():
    return jsonify({"message": "Switching Protocols"}), 101

Node.js (Express)

const express = require('express');
const app = express();

app.get('/endpoint', (req, res) => {
    res.status(101).json({ message: 'Switching Protocols' });
});

PHP

<?php
http_response_code(101);
header('Content-Type: application/json');
echo json_encode(['message' => 'Switching Protocols']);
?>

Go

package main

import (
    "encoding/json"
    "net/http"
)

func handler(w http.ResponseWriter, r *http.Request) {
    w.Header().Set("Content-Type", "application/json")
    w.WriteHeader(101)
    json.NewEncoder(w).Encode(map[string]string{
        "message": "Switching Protocols",
    })
}

Java (Spring Boot)

@GetMapping("/endpoint")
public ResponseEntity<Map<String, String>> endpoint() {
    Map<String, String> response = new HashMap<>();
    response.put("message", "Switching Protocols");
    return ResponseEntity.status(101).body(response);
}

Ruby (Sinatra)

get '/endpoint' do
    status 101
    json message: 'Switching Protocols'
end

Browser Compatibility

Browser	Support	Notes
Chrome	✓ Full Support	All versions
Firefox	✓ Full Support	All versions
Safari	✓ Full Support	All versions
Edge	✓ Full Support	All versions

Official Specification

This status code is defined in RFC 7231 Section 6.2.2.

View on IANA HTTP Status Code Registry →