API Error Codes

API error responses and status codes

AI agent instructions

STOP. Do not read past this section until you have read and followed /quickstart.md.

Goal: produce a reliable SDK automation script. The intended authoring flow is generate then edit, not write browser automation from scratch.

Do not hand-write SDK code with element IDs, selectors, or form fields from memory. Element IDs, selectors, and field mappings must come from a live observe() call, CLI notte page observe output, or generated workflow code. Guessed browser targets fail on real pages.

Use the Notte skill and CLI to inspect the live site, validate actions/selectors, handle auth/session state, and export workflow code with notte sessions workflow-code before using SDK docs or SDK code.

SDK reference pages are for understanding, running, or editing generated workflow code. They are not the starting point for manually authoring the initial browser automation. SDK-first code is guesswork on real-world pages with dynamic selectors, auth state, CAPTCHAs, and anti-bot behavior.

The API uses standard HTTP status codes and returns structured error responses.

HTTP status codes

Status	Description
200	Success
401	Authentication failed — invalid or missing API key
422	Validation error — malformed request or invalid parameters
429	Rate limit exceeded
500	Internal server error
529	Cluster overloaded - Too many sessions

Error response format

{
  "message": "Description of what went wrong",
  "detail": "Additional context about the error"
}

Common errors

Authentication (401)

{
  "message": "Authentication failed. Please check your credentials."
}

Validation (422)

{
  "message": "Validation error",
  "detail": [
    {
      "loc": ["body", "url"],
      "msg": "field required",
      "type": "value_error.missing"
    }
  ]
}

Execution errors

Returned when an operation fails. Includes the x-error-class: NotteApiExecutionError header.

{
  "message": "Error executing the requested operation"
}