Failed to initialize Stagehand: Cannot create proxy with a non-object as target or handler (Local run on MacOS)

[onlatency]

Running fully local, without API keys. Testing with Claude Desktop.
This is MacOS, so no /downloads possible. Looks like that is the issue, but I am not knowledgeable on this.

Claude config:

"stagehand": {
      "command": "node",
      "args": ["/Users/localuser/CODE/Browser-Builds/Stagehand/mcp-server-browserbase/stagehand/dist/index.js"],
      "env": {
        "DEBUG": "true"
      }
    }

Error at Claude Desktop:

{
  `url`: `https://google.com`
}
Failed to initialize Stagehand: Cannot create proxy with a non-object as target or handler
Operation logs:`

Logs:

2025-03-19T01:47:38.804Z [stagehand] [info] Message from client: {"method":"tools/call","params":{"name":"stagehand_navigate","arguments":{"url":"https://google.com"}},"jsonrpc":"2.0","id":41}
[2025-03-19T01:47:38.805Z] [DEBUG] REQUEST: {
  "timestamp": "2025-03-19T01:47:38.805Z",
  "type": "CallTool",
  "params": {
    "name": "stagehand_navigate",
    "arguments": {
      "url": "https://google.com"
    }
  }
}
[2025-03-19T01:47:38.807Z] [DEBUG] launching local browser
Error in init: Error: ENOENT: no such file or directory, mkdir '/downloads'
    at Object.mkdirSync (node:fs:1361:26)
    at /Users/localuser/CODE/Browser-Builds/Stagehand/mcp-server-browserbase/stagehand/node_modules/@browserbasehq/stagehand/dist/index.js:6037:27
    at Generator.next (<anonymous>)
    at /Users/localuser/CODE/Browser-Builds/Stagehand/mcp-server-browserbase/stagehand/node_modules/@browserbasehq/stagehand/dist/index.js:76:61
    at new Promise (<anonymous>)
    at __async (/Users/localuser/CODE/Browser-Builds/Stagehand/mcp-server-browserbase/stagehand/node_modules/@browserbasehq/stagehand/dist/index.js:60:10)
    at getBrowser (/Users/localuser/CODE/Browser-Builds/Stagehand/mcp-server-browserbase/stagehand/node_modules/@browserbasehq/stagehand/dist/index.js:5867:10)
    at Stagehand.<anonymous> (/Users/localuser/CODE/Browser-Builds/Stagehand/mcp-server-browserbase/stagehand/node_modules/@browserbasehq/stagehand/dist/index.js:6261:84)
    at Generator.next (<anonymous>)
    at /Users/localuser/CODE/Browser-Builds/Stagehand/mcp-server-browserbase/stagehand/node_modules/@browserbasehq/stagehand/dist/index.js:76:61 {
  errno: -2,
  code: 'ENOENT',
  syscall: 'mkdir',
  path: '/downloads'
}
[2025-03-19T01:47:38.810Z] [DEBUG] RESPONSE: {
  "timestamp": "2025-03-19T01:47:38.810Z",
  "type": "CallTool",
  "response": {
    "content": [
      {
        "type": "text",
        "text": "Failed to initialize Stagehand: Cannot create proxy with a non-object as target or handler"
      },
      {
        "type": "text",
        "text": "Operation logs:\n"
      }
    ],
    "isError": true
  }
}

[gench]

same error on MacOS without any API keys

[arjunmagun]

@onlatency did you find any fix for the error?

[ericpgreen2]

Same error. In my case, I've tried to add the MCP server to Cursor, and I have included BrowserBase & OpenAI API keys.