Errors

Successful responses wrap the result in data. Failed ones carry a message and a stable code:

{ "success": true, "data": { } }
{ "success": false, "error": "Experiment not found", "code": "NOT_FOUND" }

Handle errors by code. The error text is for people and can change.

Status	code	When
400	BAD_REQUEST	A query parameter is invalid or unknown
401	UNAUTHORIZED	The key is missing or invalid
404	NOT_FOUND	The experiment isn't in your store or isn't published by the API, or the path doesn't exist
405	METHOD_NOT_ALLOWED	The request isn't a GET
422	RESULTS_UNAVAILABLE	The experiment has no results the API can return
429	TOO_MANY_REQUESTS	The rate limit is used up, see Rate limits
500	INTERNAL_ERROR	Something went wrong on our side. Retry after a short wait

400: invalid parameters

errors.fieldErrors says what is wrong with each parameter:

{
  "success": false,
  "error": "Invalid query parameters",
  "code": "BAD_REQUEST",
  "errors": {
    "fieldErrors": {
      "country": ["country must be ISO 3166-1 alpha-2 country codes, e.g. US"]
    }
  }
}

Results endpoints reject unknown parameters, so a typo like contry=US fails instead of silently returning unfiltered numbers.

422: no results

reason says why: unsupported_experiment means the experiment predates our current analytics, so its results are only available in the Elevate app.