WebSocket Request response help: Some of my WebSocket requests are failing. In response It says "Internal Server Error"

Hi

I am testing WebSocket and all my WebSocket connections are okay but some of my subsequent requests are failing. My scenario is with 1000 virtual users and all 1000 users are making WebSocket connections. After making connections, all users are going for next action simultaneously and at that time some of the requests are failing with below response. My developer is saying that WebSocket connection is okay but after that he didn’t see any request coming in from that WebSocket connection and that is the reason my subsequent action is failing.

Below are my code snippet and error