I was able to reporoduce your scenario by configuring some of the fields to be obligatory (OBL) in the *Search methods* tab of a view and accessing it via the RESTful Web Service.
When some of the fields are chosen as obligatory (OBL), you need pass the value in the RESTful URL of the view. For example, if you have configured several obligatory fields named testfield1, testfield2, testfield3 then the RESTful URL to access the view should be like,
For more information, you can refer to the documents below from the Virtual DataPort Administration Guide,
1. [Input Parameters of the RESTful Web Service](https://community.denodo.com/docs/html/browse/latest/vdp/administration/restful_architecture/restful_web_service/input_parameters_of_the_restful_web_service#input-parameters-of-the-restful-web-service)
2. [RESTful Web Service](https://community.denodo.com/docs/html/browse/latest/vdp/administration/restful_architecture/restful_web_service/restful_web_service)
Hope this helps!