mastra-ai/mastra · error · SandboxFeatureNotSupportedError

FEATURE_NOT_SUPPORTED

FEATURE_NOT_SUPPORTED

Error message

Sandbox does not support computer

What it means

Thrown by requireComputer when a tool needs the sandbox's computer feature but the configured WorkspaceSandbox does not implement/declare support for it (supportsComputer returns false). SandboxComputer capability is optional per sandbox provider, so dependent tools fail fast with code FEATURE_NOT_SUPPORTED.

Source

Thrown at packages/core/src/workspace/tools/computer-helpers.ts:40

/** Default for ComputerToolConfig.screenshotDelayMs. */
export const DEFAULT_SCREENSHOT_DELAY_MS = 500;

type ComputerToolName = (typeof WORKSPACE_TOOLS.COMPUTER)[keyof typeof WORKSPACE_TOOLS.COMPUTER];

/**
 * Extract the computer capability from the workspace sandbox in the tool
 * execution context. Throws if the workspace has no sandbox or the sandbox
 * doesn't support the computer capability.
 */
export function requireComputer(context: ToolExecutionContext): {
  workspace: Workspace;
  sandbox: WorkspaceSandbox;
  computer: SandboxComputer;
} {
  const { workspace, sandbox } = requireSandbox(context);
  if (!supportsComputer(sandbox)) {
    throw new SandboxFeatureNotSupportedError('computer');
  }
  return { workspace, sandbox, computer: sandbox.computer };
}

/** Resolve the per-tool ComputerToolConfig from the workspace tools config. */
export function getComputerToolConfig(
  workspace: Workspace,
  toolName: ComputerToolName,
): ComputerToolConfig | undefined {
  return workspace.getToolsConfig()?.[toolName];
}

/**
 * Format a screenshot as a MediaToolResult, falling back to text-only output
 * when the image exceeds the configured size cap (so huge base64 payloads
 * don't blow up the model context or storage).
 */
export function screenshotToResult(

View on GitHub (pinned to 75dd419e61)

Solutions

1. Configure a sandbox that supports computer use (one exposing sandbox.computer)
2. Guard tool availability: only register/expose computer tools when supportsComputer(sandbox) is true
3. Check for the FEATURE_NOT_SUPPORTED code in catch blocks and fall back to shell-based tools
4. Verify the sandbox provider/version actually implements the computer interface

Example fix

// before
const sandbox = createShellSandbox();
// after
const sandbox = supportsComputer(desiredSandbox) ? desiredSandbox : createComputerSandbox();

if (!workspace.sandbox || !supportsComputer(workspace.sandbox)) {
  throw new Error('computer tools unavailable');
}

function hasComputer(s: WorkspaceSandbox): s is WorkspaceSandbox & { computer: SandboxComputer } {
  return typeof (s as any).computer === 'object' && (s as any).computer !== null;
}

try {
  return await computerTool.execute(ctx);
} catch (e: any) {
  if (e?.code === 'FEATURE_NOT_SUPPORTED' || /does not support computer/i.test(e?.message ?? '')) {
    return { error: 'This sandbox does not support computer use; use shell tools instead.' };
  }
  throw e;
}

When it happens

Trigger: Invoking computer tools (screenshot, click, type, etc.) against a workspace whose sandbox lacks a computer implementation; using a sandbox provider that only supports processes/filesystem.

Common situations: Local or container sandboxes without desktop/browser automation; switching sandbox providers and assuming computer support; configuring computer tool config without a matching sandbox capability.

Related errors

• Sandbox provider "${sandbox.provider}" does not support netw
• Sandbox provider "${sandbox.provider}" does not support exec
• Sandbox provider "${sandbox.provider}" does not support exec
• Sandbox provider "${options.sandbox.provider}" does not supp
• sandbox_command

AI-assisted analysis of mastra-ai/mastra@75dd419e61 (2026-08-30). Data as JSON: /api/errors/5f9deec353da6873. Report an issue: GitHub.