The POST /{environmentId}/flows/{flowId} operation initiates an action to allow users to sign on with a username. The request body requires only the username attribute. The username value is verified in this action. This operation uses the application/vnd.pingidentity.user.lookup+json custom media type as the content type in the request header.

The status property value in the response indicates that the one-time password validation step used in a multi-factor authentication flow is a required action. The response includes the validateOTP HAL link to initiate this required step.