Error Handling

The API uses standard HTTP status codes and returns errors as JSON.

Error Format

{
  "error": "Description of what went wrong"
}

Code	Meaning
`400`	Bad request - invalid input or missing required fields
`401`	Unauthorized - invalid or missing API key
`404`	Not found - resource does not exist
`409`	Conflict - resource is in an incompatible state (e.g., starting a non-pending experiment)
`413`	Payload too large - request body exceeds size limit
`415`	Unsupported media type - invalid content type
`500`	Internal server error

When request body validation fails, the error message describes the first validation issue:

{
  "error": "Expected string, received number"
}

Missing required field:

{ "error": "Required" }

Invalid UUID:

{ "error": "Invalid uuid" }

State conflict:

{ "error": "Can only update pending experiments" }

See the full API Reference for endpoint-specific error details.