CD
Cloudflare Developers•2mo ago
Noel

Errors in websocket worker tail

I just made my very first websocket worker and deployed it. It works just fine, however when I tried to see the logs with tail I encountered some strange behavior: no logs show while the connection is active and when i disconnect all log entries show up with two identical errors stating: Error: The Workers runtime canceled this request because it detected that your Worker's code had hung and would never generate a response. Refer to: https://developers.cloudflare.com/workers/observability/errors/ the linked page stated that I need the following block to prevent this: 
server.addEventListener("close", () => {
    server.close();
});
server.addEventListener("close", () => {
    server.close();
});
however after adding it the same issue remains. Output: 
GET https://api-dev.example.com/charger/ocpp?chargerId=1 - Exception Thrown @ 2025. 10. 15. 10:46:16
  (log) OCPP-[C(1)]: Connection attempt.
  (log) OCPP-[C(1)->S]: [2, "36799101", "BootNotification", {...}]
  (log) OCPP-[S->C(1)]: [3,"36799101",{"currentTime":"2025-10-15T08:46:22.779Z","interval":0,"status":"Accepted"}]
✘ [ERROR]   Error: The Workers runtime canceled this request because it detected that your Worker's code had hung and would never generate a response. Refer to: https://developers.cloudflare.com/workers/observability/errors/


✘ [ERROR]   Error: The Workers runtime canceled this request because it detected that your Worker's code had hung and would never generate a response. Refer to: https://developers.cloudflare.com/workers/observability/errors/
GET https://api-dev.example.com/charger/ocpp?chargerId=1 - Exception Thrown @ 2025. 10. 15. 10:46:16
  (log) OCPP-[C(1)]: Connection attempt.
  (log) OCPP-[C(1)->S]: [2, "36799101", "BootNotification", {...}]
  (log) OCPP-[S->C(1)]: [3,"36799101",{"currentTime":"2025-10-15T08:46:22.779Z","interval":0,"status":"Accepted"}]
✘ [ERROR]   Error: The Workers runtime canceled this request because it detected that your Worker's code had hung and would never generate a response. Refer to: https://developers.cloudflare.com/workers/observability/errors/


✘ [ERROR]   Error: The Workers runtime canceled this request because it detected that your Worker's code had hung and would never generate a response. Refer to: https://developers.cloudflare.com/workers/observability/errors/
1 Reply
Noel
NoelOP•2mo ago
Code with some checks removed to fit in message: 
export default {
fetch(request, env, ctx) {
const [client, server] = new WebSocketPair();
const chargerId = new URL(request.url).searchParams.get('chargerId');

console.log("OCPP-[C(" + chargerId + ")]: Connection attempt.");

server.accept();
server.addEventListener('message', async event => {
    console.log("OCPP-[C(" + chargerId + ")->S]: " + event.data);
    try {
        let res = await process(event.data, chargerId, env);
        console.log("OCPP-[S->C(" + chargerId + ")]: " + res);
        event.target.send(res)
    } catch (e) {
        console.error("OCPP-[S->C(" + chargerId + ")]: ", e)
    }
});

server.addEventListener("close", () => {
    server.close();
});

return new Response(null, {status: 101,webSocket: client});
}
}
export default {
fetch(request, env, ctx) {
const [client, server] = new WebSocketPair();
const chargerId = new URL(request.url).searchParams.get('chargerId');

console.log("OCPP-[C(" + chargerId + ")]: Connection attempt.");

server.accept();
server.addEventListener('message', async event => {
    console.log("OCPP-[C(" + chargerId + ")->S]: " + event.data);
    try {
        let res = await process(event.data, chargerId, env);
        console.log("OCPP-[S->C(" + chargerId + ")]: " + res);
        event.target.send(res)
    } catch (e) {
        console.error("OCPP-[S->C(" + chargerId + ")]: ", e)
    }
});

server.addEventListener("close", () => {
    server.close();
});

return new Response(null, {status: 101,webSocket: client});
}
}

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