Errors

The Finetuning.ai API uses standard HTTP status codes and returns consistent error responses.

Error response format

All errors follow the format:

{
  "error": {
    "code": "...",
    "message": "..."
  }
}

Code	Status	Description
`MISSING_API_KEY`	401	X-API-Key header was not provided
`INVALID_API_KEY`	401	API key is malformed, revoked, or does not exist
`PRO_PLAN_REQUIRED`	403	Your subscription does not include API access
`RATE_LIMITED`	429	Too many requests — wait and retry
`VALIDATION_ERROR`	400	Request body is missing or has invalid fields
`MONTHLY_LIMIT_REACHED`	402	No generations remaining this month
`QUEUE_FULL`	429	Too many generations in progress
`GENERATION_FAILED`	500	Generation queue submission failed
`NOT_FOUND`	404	Resource not found
`INTERNAL_ERROR`	500	Unexpected server error

{
  "error": {
    "code": "INVALID_API_KEY",
    "message": "API key is malformed, revoked, or does not exist"
  }
}

Fix: Ensure you're using the X-API-Key header (not Authorization: Bearer). Double-check for extra whitespace or newlines in your key.

{
  "error": {
    "code": "MONTHLY_LIMIT_REACHED",
    "message": "No generations remaining this month"
  }
}

Fix: Upgrade your plan or wait for your monthly limit to reset at finetuning.ai/dashboard.

{
  "error": {
    "code": "VALIDATION_ERROR",
    "message": "duration must be between 10 and 180 seconds"
  }
}

Fix: Check the message field for details on which fields are invalid.

If a generation stays in processing for more than 5 minutes, it may have failed silently. Contact support.

If you're encountering errors not listed here, visit the Support page.