API - Invalid Authorization header - StatusCode 400

Problem

When attempting to use the API the following message is received:

{
  "error": {
    "message": "Invalid Authorization header. You need to provide your API key in the Authorization header using Token prefix (e.g. 'Authorization: Token YOUR_SECRET_KEY'). See https://securityscorecard.readme.io/docs/getting-started for details, or we can help at support@securityscorecard.io",
    "statusCode": 400
  }
}

Solution

'Token ' with a space must be included before the API token. See screenshot below.