t8y2/dbx · error · DuckDbWorkerError

invalid_json

invalid_json

Error message

Invalid worker request JSON: {err}

What it means

run_stdio_worker reads newline-delimited JSON requests from stdin and parses them with serde_json; any malformed line yields an invalid_json error response (with empty request id) that is written back to stdout, and processing continues. The error message embeds the serde error describing exactly what was wrong.

Source

Thrown at agents/drivers/duckdb/src/runtime.rs:440

        let line = lines.next_line().await.map_err(|e| e.to_string())?;
        let Some(line) = line else {
            // Parent closed stdin (exit or crash). Idle workers checkpoint and
            // remove their WAL on the normal return path; a worker still running
            // a query must not wait for it (nor drop a poisoned connection),
            // so it keeps the legacy immediate exit and the WAL replays on the
            // next open.
            if !runtime.close_session_for_shutdown() {
                std::process::exit(0);
            }
            break;
        };
        if line.trim().is_empty() {
            continue;
        }
        let request: DuckDbWorkerRequest = match serde_json::from_str(&line) {
            Ok(request) => request,
            Err(err) => {
                let response = DuckDbWorkerResponse::err(
                    "",
                    DuckDbWorkerError::new("invalid_json", format!("Invalid worker request JSON: {err}")),
                );
                write_response(stdout.clone(), &response).await;
                continue;
            }
        };
        let result = runtime.handle_request(request, stdout.clone()).await;
        if let Some(response) = result.response {
            write_response(stdout.clone(), &response).await;
        }
        if result.shutdown {
            break;
        }
    }
    Ok(())
}

View on GitHub (pinned to c0390bff16)

Solutions

1. Log the offending line and compare against the DuckDbWorkerRequest schema expected by the worker binary; align host and worker versions.
2. Ensure each request is written as exactly one complete JSON object followed by a newline, and flush after each write.
3. Validate/serialize requests with the same serde types (or the generated bindings) instead of hand-building JSON strings.

Example fix

// before
stdin.write(`{"id":1,"method":execute}`); // invalid JSON, unquoted method
// after
const req = JSON.stringify({ id: "1", method: "execute", params: {} });
stdin.write(req + "\n");

// TS: validate before writing to the worker's stdin
const req = { id, method, params };
const line = JSON.stringify(req);
JSON.parse(line); // throws locally if serialization is broken
workerStdin.write(line + "\n");

function isValidRequest(r: unknown): r is DuckDbWorkerRequest {
  return typeof r === "object" && r !== null
    && typeof (r as any).id === "string"
    && typeof (r as any).method === "string";
}

if (response.error?.code === "invalid_json") {
  console.error("request rejected:", response.error.message);
  // fix serializer / version-align host and worker, then resend
}

When it happens

Trigger: Writing a line to the worker's stdin (runtime.rs:440) that is not a valid DuckDbWorkerRequest JSON: truncated output, wrong field names/types, duplicate fields, or non-UTF8/binary garbage on the pipe.

Common situations: Host and worker binary version mismatch (schema drift in DuckDbWorkerRequest); host writing partial JSON due to a pipe buffering bug; a parent process flushing logs/JSON into the same stdin; console noise injected into the protocol stream.

Related errors

• encode subscription group config: %w
• {key} is required
• Failed to migrate JSON data
• Failed to migrate JSON data
• duckdb_worker_exited

AI-assisted analysis of t8y2/dbx@c0390bff16 (2026-09-05). Data as JSON: /api/errors/38b606114a143bf7. Report an issue: GitHub.