Seeing "WebSocket connection is missing at ChatService.startSession" in the log

Questions
1

What is the error message (if any)?

“WebSocket connection is missing at ChatService.startSession”

Please share your workflow

n/a

Share the output returned by the last node

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Information on your n8n setup

  • n8n version: 2.4.7
  • Database (default: SQLite): postgres
  • n8n EXECUTIONS_PROCESS setting (default: own, main):
  • Running n8n via Docker(AWS Fargate):
  • Operating system: n/a
2

Hi @Neil_Carmichael

Does the WebSocket handshake reach the n8n container successfully (HTTP 101 Switching Protocols), or is it being terminated earlier by the ALB, WAF, or another proxy in front of it?

I’m seeing the error WebSocket connection is missing at ChatService.startSession, which usually indicates that the WebSocket upgrade is not completing end-to-end. The n8n instance itself is running on AWS Fargate with Postgres, so I’m trying to confirm whether something in front of the container (ALB, WAF, or reverse proxy) is blocking or stripping the Upgrade / Connection headers, enforcing a low idle timeout, or otherwise interfering with WebSocket traffic.

3

I found the solution, we needed to add N8N_PUSH_BACKEND=websocket to the task defintion

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