If you are experiencing difficulty in connecting to and using the API, check the following items:

• The URL that you are using is correct.
• The application is running.
• The username that you are using to invoke the API has access to the application and the data that you are attempting to retrieve.
• The request body JSON is valid and properly formatted.
• The request body contains the required fields in JSON for create and update operations.
• The request content-type is 'application/json'.