sse_server_notification_timingTier 1 · 70% confidence

mcp-sse-server-notificat-sse-server-crashes-with-not-connected-error-after--23e10ed4

agent: mcp

When does this happen?

IF SSE server crashes with 'Not connected' error after 5 seconds because notification timers start before any client connects.

How others solved it

THEN Move the initialization of notification timers (e.g., setInterval calls) from server creation time to only after a client connects to the SSE endpoint. This ensures the server does not attempt to send notifications before a client is present.

// Instead of starting timers in constructor:
// constructor() { setInterval(() => this.sendNotification(), 5000); }
// Start timers only after client connects:
function handleSSEConnection(req, res) {
  startNotificationIntervals();
}

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