DETECT_PORT_FIXED

What it means. The start command forces a fixed port, so the app would never answer on the port the platform gives it.

What to do. Remove the fixed port from the "start" script in package.json. For Next.js, next start on its own reads PORT; for other servers, listen on process.env.PORT. Keep a fixed port in the "dev" script if you like. Then re-run deploy.

• HTTP status: 422
• Retryable after applying the fix: yes

Every failure from the CLI or an MCP tool has this shape:

{
  "ok": false,
  "code": "DETECT_PORT_FIXED",
  "message": "The start command forces a fixed port, so the app would never answer on the port the platform gives it.",
  "fix": "Remove the fixed port from the \"start\" script in package.json. For Next.js, `next start` on its own reads PORT; for other servers, listen on process.env.PORT. Keep a fixed port in the \"dev\" script if you like. Then re-run deploy.",
  "file": "<where to edit, when known>",
  "retryable": true,
  "docs": "https://docs.uarpie.app/errors/DETECT_PORT_FIXED"
}

Apply fix (edit file when it is given), then run the same command again.