API Errors

Every request to the SigOpt API returns an HTTP status code. Status code 2XX indicates a successful call and the response will contain the requested resource. Other status codes indicate failure. The response bodies will have the following format:

  "error": {
    "message": "No API token provided."

HTTP Error Codes

Error CodeHTTP DefinitionDescription



The request has succeeded.


Client Error

There's something wrong with your request! Please modify and try again.


Bad Request

We could not understand your request, or a parameter is missing or incorrect.



This request requires authentication.



We can read your authentication but it is not the correct authentication for this endpoint.


Not Found

We were unable to find the requested resource.


Method Not Allowed

Our API supports the methods GET, PUT, POST, and DELETE. Not all endpoints support all methods, so double check the API endpoints reference .



The request could not be completed because there is a conflicting resource that already exists. This can occur if you are reusing an existing ID, or trying to operate on expired data.


Too Many Requests

You've sent too many requests too quickly. Try again later.


Server Error

Something went wrong on our end! We're working to fix it.

Still not seeing a solution? Browse specific errors below, or post on the community page and we can help!


No API token provided

We cannot find the API token in your request (you may be providing the wrong header). Read more about authenticating.

This endpoint requires a valid API token

You have provided an API token in the correct header, but one of several issues has arisen:

  • The provided API token does not match a client

  • The client matched by the API token does not have access to this endpoint

Your first step should be to verify that you are attempting to access one of our public API endpoints. Next, ensure your are authenticating with the correct token.

Exceeded plan limits

You have exceeded one or more of the limits of your plan and its associated plan rules.

Missing required json key

We use JSON data to pass parameters for POST and PUT requests. If you are seeing this error, you are either missing a required key in your JSON object, or we are not able to parse the JSON data correctly. Try adding the Content-Type: application/json header to your request, and double-check that all your JSON arguments are provided correctly.

Why am I getting repeated suggestions?

You are most likely using your development API token, which creates experiments in development mode and suggests assignments that are only suitable for debugging.

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