Websocketexception: connection to was not upgraded to websocket

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Websocketexception: Connection to [URL] was not upgraded to WebSocket

A WebSocketException with the message “Connection to [URL] was not upgraded to WebSocket” occurs when the server fails to upgrade the HTTP connection to the WebSocket protocol. This can happen due to various reasons, such as incorrect server configuration, firewall restrictions, or compatibility issues.

Possible Causes:

  1. Incorrect Server Configuration: The server may not have been properly configured to support WebSocket connections. The server-side code and configuration should be set up to handle the WebSocket protocol.
  2. Firewall Restrictions: Firewalls or network restrictions may be blocking the WebSocket connection. Ensure that the necessary ports are open and the WebSocket protocol is allowed through the firewall.
  3. Compatibility Issues: The client-side and server-side WebSocket implementations might not be fully compatible. Make sure both client and server are using compatible WebSocket libraries or frameworks.

Example:

Let’s consider an example using JavaScript and a WebSocket library like Socket.io:

<!DOCTYPE html>
<html>
<head>
  <script src="https://cdn.socket.io/socket.io-3.1.1.js"></script>
</head>
<body>
  <script>
    // Connect to WebSocket server
    const socket = io('http://example.com');
    
    // Handle connection event
    socket.on('connect', () => {
      console.log('Connected to WebSocket');
      // Perform further actions or communication
    });
    
    // Handle connection error
    socket.on('connect_error', (error) => {
      console.error('WebSocket connection error:', error.message);
      // Perform error handling as needed
    });
  </script>
</body>
</html>

In this example, we’re trying to connect to a WebSocket server running at “http://example.com” using the Socket.io library. If the connection is successfully upgraded to the WebSocket protocol, the “connect” event will be triggered, indicating a successful handshake. Otherwise, if the connection fails to upgrade, the “connect_error” event will be triggered, allowing us to handle the error.

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