This usually indicates that the input data is incorrect, make sure that the body of your request is valid JSON. We recommend using an online JSON validator or built in validators in your IDE:

Make sure you have defined the content type as "application/json"

Make sure the { access: { id: "XYZ" } } refers to the Key you want to use (you find the Access Id when you select the Key in the Parakey Web Portal).

Make sure that the key with id XYZ has "Allow API" enabled