openai/codex · error

hosted MCP event server was removed

Error message

hosted MCP event server was removed

What it means

Error "hosted MCP event server was removed" thrown in openai/codex.

Source

Thrown at codex-rs/codex-mcp/src/resource_client.rs:88

    request: Option<CancellableEventStreamRequest>,
    runtime_handle: Handle,
    connection: Option<Arc<McpServerConnection>>,
    hosted_event_server_removals: watch::Receiver<()>,
}

impl McpEventStream {
    /// Receives the next raw lifecycle notification for this subscription.
    pub async fn recv(&mut self) -> Result<Option<McpEventNotification>> {
        let Some(request) = self.request.as_mut() else {
            return Ok(None);
        };

        tokio::select! {
            biased;

            Ok(()) = self.hosted_event_server_removals.changed() => {
                self.cancel();
                Err(anyhow!("hosted MCP event server was removed"))
            }
            Some(notification) = request.notifications.recv() => {
                let metadata = notification.get_meta().0.0.clone();
                let mut params = notification.params;
                if !metadata.is_empty() {
                    params.get_or_insert_with(|| json!({}))["_meta"] = Value::Object(metadata);
                }
                Ok(Some(McpEventNotification {
                    method: notification.method,
                    params,
                }))
            }
            response = &mut request.handle.rx => {
                self.request = None;
                self.connection = None;

                match response {
                    Ok(Ok(_))

View on GitHub (pinned to 339751715c)

Solutions

1. Re-register or reconnect the hosted MCP event server and retry the operation.

When it happens

Trigger: Thrown at codex-rs/codex-mcp/src/resource_client.rs:88 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of openai/codex@339751715c (2026-08-25). Data as JSON: /api/errors/6b9cf6c50795eea4. Report an issue: GitHub.