MCP Perplexity Ask Server: ${APPDATA} Fix error under Windows

If you are setting up an MCP server under Claude for Desktop on Windows, you may encounter an annoying error with ${APPDATA}. It usually appears in the log if the server does not load – typically: ENOENT or the server simply does not appear in Claude. Don’t worry, here is the quick solution.

🔍 The problem

Windows does not automatically recognize environment variables such as ${APPDATA} in the MCP config file. As a result, paths are not resolved correctly – and the server does not start.

Artificial intelligence can be so helpful if it works.

✅ The solution

You have to set the %APPDATA% path manually. This is how it works:

"APPDATA": "C:\\Users\\your-user-name\\AppData\\Roaming\\"

1. Open the claude_desktop_config.json file (located under %APPDATA%\Claude\).
2. Add or adjust the affected server entry, e.g:

{
  "serverConfig": {
    "perplexity-ask": {
      "command": "npx",
      "args": [
        "-y",
        "server-perplexity-ask"
      ],
      "env": {
        "PERPLEXITY_API_KEY": "your-perplexity-key",
        "APPDATA": "C:\\Users\\your-user-name\\AppData\\Roaming\\"
      }
    }
  }
}

Replace your-user-name with your Windows user name.

3. Save, restart Claude – and voilà: The server should now be running.

🧪 Bonus tip

If npx is not found, make sure that npm is installed globally:

npm install -g npm

With this small adjustment, your MCP server will run smoothly – and you can finally make full use of Claude Desktop 🚀

My log file error:

npm error code ENOENT
npm error syscall lstat
npm error path C:\Users\user\AppData\Local\AnthropicClaude\app-0.9.3\${APPDATA}
npm error errno -4058
npm error enoent ENOENT: no such file or directory, lstat 'C:\Users\user\AppData\Local\AnthropicClaude\app-0.9.3\${APPDATA}'
npm error enoent This is related to npm not being able to find a file.
npm error enoent