mastra-ai/mastra · error

allowSystemBinaries: false is not supported by seatbelt (mac

Error message

allowSystemBinaries: false is not supported by seatbelt (macOS). Use bubblewrap on Linux or remove this restriction.

What it means

generateSeatbeltProfile is fail-closed: macOS seatbelt (SBPL) cannot restrict process-exec enough to exclude system binaries, so a NativeSandboxConfig with allowSystemBinaries: false is rejected rather than generating a profile that silently allows more than requested.

Source

Thrown at packages/core/src/workspace/sandbox/native-sandbox/seatbelt.ts:88

  }
}

/**
 * Generate a seatbelt profile for the given configuration.
 *
 * The profile:
 * - Allows all file reads (can't restrict with subpath on macOS)
 * - Restricts file writes to temp directories, configured writable paths, and the workspace unless read-only
 * - Blocks network unless explicitly allowed
 *
 * @param workspacePath - The workspace directory to sandbox
 * @param config - Additional sandbox configuration
 * @returns The generated SBPL profile content
 */
export function generateSeatbeltProfile(workspacePath: string, config: NativeSandboxConfig): string {
  // Fail-closed: seatbelt cannot restrict process-exec, so reject unsupported config
  if (config.allowSystemBinaries === false) {
    throw new Error(
      'allowSystemBinaries: false is not supported by seatbelt (macOS). ' +
        'Use bubblewrap on Linux or remove this restriction.',
    );
  }

  const lines: string[] = [];

  // Version and default deny
  lines.push('(version 1)');
  // Marker comment, so a profile Mastra wrote is still known as ours on a later run.
  lines.push(GENERATED_PROFILE_MARKER);
  lines.push('(deny default (with message "mastra-sandbox"))');
  lines.push('');

  // Process permissions
  lines.push('; Process permissions');
  lines.push('(allow process-exec)');
  lines.push('(allow process-fork)');

View on GitHub (pinned to 75dd419e61)

Solutions

1. Remove `allowSystemBinaries: false` from the config on macOS.
2. Set allowSystemBinaries: true (or omit it) when the seatbelt backend is used.
3. Condition the config on process.platform so Linux keeps bubblewrap's strict setting.
4. If you need that restriction on macOS, use a different isolation mechanism (e.g. a container/VM).

Example fix

// before
const config = { allowSystemBinaries: false };
// after
const config = process.platform === 'darwin'
  ? {} // seatbelt cannot support this restriction
  : { allowSystemBinaries: false };

if (process.platform === 'darwin' && config.allowSystemBinaries === false) {
  throw new Error('allowSystemBinaries:false unsupported on macOS seatbelt; adjust config');
}

function isSeatbeltCompatible(config: { allowSystemBinaries?: boolean }): boolean {
  return process.platform !== 'darwin' || config.allowSystemBinaries !== false;
}

try {
  const sb = createNativeSandbox(config);
} catch (e) {
  if (e instanceof Error && /seatbelt \(macOS\)/.test(e.message)) {
    // fall back to a seatbelt-safe config
    const { allowSystemBinaries, ...rest } = config;
    return createNativeSandbox(rest);
  }
  throw e;
}

When it happens

Trigger: Creating a native sandbox with `allowSystemBinaries: false` on macOS (seatbelt backend), e.g. passing { allowSystemBinaries: false } in workspace/native sandbox config while running on darwin.

Common situations: Sharing one sandbox config between Linux (bubblewrap) and macOS (seatbelt) machines/CI; tightening security settings after reading Linux-focused docs; a hardened default inherited from a Linux-oriented template.

Related errors

• execa is not available in Cloudflare Workers
• Sandbox provider "${sandbox.provider}" does not support netw
• Sandbox provider "${sandbox.provider}" did not expose a publ
• Woke sandbox but the Mastra server did not become healthy at
• createSandboxProxy requires an Edge Config connection string

AI-assisted analysis of mastra-ai/mastra@75dd419e61 (2026-08-30). Data as JSON: /api/errors/4d3d216dd5110032. Report an issue: GitHub.