openclaw - 💡(How to fix) Fix [Bug]: agent/embedded ws-stream handshake returns HTTP 500 on 2026.3.28 (falls back to HTTP every turn) [2 comments, 2 participants]

warn agent/embedded [ws-stream] WebSocket connect failed for session=<new-or-old-session-id>; falling back to HTTP. error=Error: Unexpected server response: 500

Seen repeatedly across multiple session IDs, e.g.: 4a80b376-db9f-41cd-bc13-ee95f34678ba cb216ed7-73b0-43db-8b5f-5fedbaffdfce slug-generator-1774819131410 At same times, gateway ws for UI is healthy: Copy info gateway/ws webchat connected ... client=openclaw-control-ui webchat v2026.3.28 info gateway/ws ⇄ res ✓ chat.history / models.list / node.list / device.pair.list / health

Reproduces after multiple gateway restarts. Reproduces with both old and brand-new sessions. Channel switch to beta did not change behavior because beta currently resolves to same build (2026.3.28).

Fix Plan

To resolve the WebSocket streaming issue, we need to update the WebSocket handshake handling in the agent/embedded module.

Here are the steps to fix the issue:

• Update the ws-stream module to handle HTTP 500 errors during WebSocket handshake.
• Add retry logic to reconnect to the WebSocket endpoint after a failed handshake.
• Implement error logging to track and debug WebSocket connection issues.

Example code changes:

// Update ws-stream module to handle HTTP 500 errors
const WebSocket = require('ws');
const wss = new WebSocket.Server({ port: 8080 });

wss.on('connection', (ws) => {
  ws.on('error', (error) => {
    if (error.statusCode === 500) {
      // Retry WebSocket connection after 500 error
      setTimeout(() => {
        ws.connect();
      }, 1000);
    }
  });
});

Verification

To verify the fix, follow these steps:

• Restart the gateway and open the control UI.
• Create a fresh chat/session and send a ping.
• Observe the logs to ensure the WebSocket connection is established successfully.
• Check for any error messages related to WebSocket connections.

Extra Tips

• Ensure that the WebSocket endpoint is properly configured and accessible.
• Monitor the logs for any recurring issues related to WebSocket connections.
• Consider implementing additional error handling and logging mechanisms to improve debugging and troubleshooting.