openai/codex · error · HandshakeError

handshaking with MCP server failed: {source}

Error message

handshaking with MCP server failed: {source}

What it means

Error "handshaking with MCP server failed: {source}" thrown in openai/codex.

Source

Thrown at codex-rs/rmcp-client/src/streamable_http_retry.rs:247

    let duration = timeout.unwrap_or(fallback);
    anyhow!("timed out handshaking with MCP server after {duration:?}")
}

pub(super) async fn sleep_with_retry_deadline(delay: Duration, deadline: Option<Instant>) -> bool {
    if let Some(deadline) = deadline {
        let remaining = deadline.saturating_duration_since(Instant::now());
        if remaining.is_zero() {
            return false;
        }
        time::timeout(remaining, time::sleep(delay)).await.is_ok()
    } else {
        time::sleep(delay).await;
        true
    }
}

#[derive(Debug, thiserror::Error)]
#[error("handshaking with MCP server failed: {source}")]
pub(super) struct HandshakeError {
    #[source]
    pub(super) source: rmcp::service::ClientInitializeError,
}

#[cfg(test)]
#[path = "streamable_http_retry_tests.rs"]
mod tests;

View on GitHub (pinned to 339751715c)

When it happens

Trigger: Thrown at codex-rs/rmcp-client/src/streamable_http_retry.rs:247 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/3ad6342cf8af9807. Report an issue: GitHub.