WSO2 API Manager presents error 101503 when testing new API

[barbozasantoz]

Description: I installed wso2 api-management using Docker and I'm getting this error: 101503 when testing the API

Suggested Labels: WSO2 API Manager, Docker, WSO2 API Manager with Docker

Steps to reproduce: I performed the installation using Docker. Basically I followed the steps present here.

After that I created an API following these steps here.

So when I try to test the application I have this error:

{
  "code": "101503",
  "type": "Status report",
  "message": "Runtime Error",
  "description": "Error connecting to the back end"
}

The error presenting in WSO2: erro_wso2.pdf
The working application: erro_wso2_2.pdf

Do any good souls know how to help?