Hmbown/CodeWhale · error · StreamableSendError::Other

MCP server rejected the request with ; the session is no…

Error message

MCP server {} rejected the request with {status}; the session is no longer accepted. {hint}

What it means

After a failed OAuth refresh attempt (previous case) is exhausted, or when the auth path is exhausted, a rejected status on the MCP POST means the server no longer accepts the session. The client surfaces the masked server URL, the status, and a hint tailored to whether OAuth is configured, telling the developer the session must be re-established.

Solutions

Re-authenticate / re-run the OAuth flow for the MCP server
If OAuth is not configured but the server requires auth, configure OAuth credentials
Retry the request so a fresh session id is negotiated
Check server-side session/auth configuration and logs

Defensive patterns

Strategy: retry

Try / catch

match client.send(request).await {
    Err(e) if e.to_string().contains("session is no longer accepted") => {
        // start a fresh session (drop stale session id) and retry once
        client.reset_session();
        client.send(request).await
    }
    other => other,
}

Prevention

Re-negotiate the session id after any server restart or 4xx session rejection
Configure OAuth when the server requires authentication
Don't cache session ids across long idle periods

When it happens

Trigger: send() receives an auth-rejection status (e.g. 401/403) from the MCP server's POST response after the refresh-and-retry path did not apply or completed, and unauthorized_session_hint() builds guidance based on whether OAuth is configured.

Common situations: Server restarted and invalidated the session id; session revoked server-side; tokens expired and no OAuth configured; stale session id replayed after server state loss.

Related errors

AI-assisted analysis of Hmbown/CodeWhale@73e0f67d83 (2026-09-22). Data as JSON: /api/errors/8b3ce135fa508daf. Report an issue: GitHub.

Appendix: source

Thrown at crates/tui/src/mcp/streamable_http.rs:128

            if status == StatusCode::UNAUTHORIZED || status == StatusCode::FORBIDDEN {
                if !retried && let Some(oauth) = self.auth.oauth.as_ref() {
                    match oauth.force_refresh().await {
                        Ok(()) => {
                            retried = true;
                            continue;
                        }
                        Err(refresh_error) => {
                            return Err(StreamableSendError::Other(anyhow::anyhow!(
                                "MCP server {} rejected the request with {status} and refreshing the OAuth session failed: {refresh_error:#}. {hint}",
                                mask_url_secrets(&self.url),
                                hint = oauth_refresh_failed_hint(),
                            )));
                        }
                    }
                }
                let hint = unauthorized_session_hint(self.auth.oauth_configured);
                return Err(StreamableSendError::Other(anyhow::anyhow!(
                    "MCP server {} rejected the request with {status}; the session is no longer accepted. {hint}",
                    mask_url_secrets(&self.url),
                )));
            }

            if !status.is_success() {
                let body_excerpt = bounded_body_excerpt(response, ERROR_BODY_PREVIEW_BYTES).await;
                let stale_session = self.session_id.is_some()
                    && is_streamable_http_stale_session_status(status, &body_excerpt);
                let body_excerpt = self.auth.server_error_preview(&body_excerpt);
                if stale_session {
                    return Err(StreamableSendError::StaleSession(format!(
                        "status={status} body={body_excerpt}"
                    )));
                }
                if is_streamable_http_incompatible_status(status) {
                    return Err(StreamableSendError::Incompatible(format!(
                        "status={status} body={body_excerpt}"

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