paperclipai/paperclip · error · Error

Sandbox callback bridge wrote invalid readiness JSON

Error message

Sandbox callback bridge wrote invalid readiness JSON: ${error instanceof Error ? error.message : String(error)}

What it means

Protocol-parsing failure during bridge startup: the readiness wait loop completed but the bridge's ready-file JSON (host/port/pid) failed to parse, so the worker's listen address cannot be determined from the remote output.

Solutions

1. Retry starting the bridge; readiness JSON was malformed.
2. Check the bridge queue directory for corruption.

When it happens

Trigger: Thrown at packages/adapter-utils/src/sandbox-callback-bridge.ts:1660 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of paperclipai/paperclip@3f1d897a7c (2026-08-18). Data as JSON: /api/errors/ebbc62c6e6bf953f. Report an issue: GitHub.

Appendix: source

Thrown at packages/adapter-utils/src/sandbox-callback-bridge.ts:1800

  bridgeAsset?: SandboxCallbackBridgeAsset | null;
  host?: string;
  port?: number | null;
  pollIntervalMs?: number | null;
  responseTimeoutMs?: number | null;
  timeoutMs?: number | null;
  nodeCommand?: string;
  shellCommand?: "bash" | "sh" | null;
  maxQueueDepth?: number | null;
  maxBodyBytes?: number | null;
}): Promise<StartedSandboxCallbackBridgeServer> {
  const timeoutMs = normalizeTimeoutMs(input.timeoutMs, DEFAULT_BRIDGE_RESPONSE_TIMEOUT_MS);
  const shellCommand = preferredShellForSandbox(input.shellCommand);
  const directories = sandboxCallbackBridgeDirectories(input.queueDir);
  let remoteEntrypoint = path.posix.join(input.assetRemoteDir, SANDBOX_CALLBACK_BRIDGE_ENTRYPOINT);
  if (input.bridgeAsset) {
    const assetSync = await syncSandboxCallbackBridgeEntrypoint({
      runner: input.runner,
      remoteCwd: input.remoteCwd,
      assetRemoteDir: input.assetRemoteDir,
      bridgeAsset: input.bridgeAsset,
      timeoutMs,
      shellCommand,
    });
    remoteEntrypoint = assetSync.remoteEntrypoint;
  }
  const env = buildSandboxCallbackBridgeEnv({
    queueDir: input.queueDir,
    bridgeToken: input.bridgeToken,
    host: input.host,
    port: input.port,
    pollIntervalMs: input.pollIntervalMs,
    responseTimeoutMs: input.responseTimeoutMs,
    maxQueueDepth: input.maxQueueDepth,
    maxBodyBytes: input.maxBodyBytes,
  });
  const nodeCommand = input.nodeCommand?.trim() || "node";

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