Launching Roku device through localhost URL without deeplinking

I am actually trying to launch the app using following endpoint:~

POST {localhost}v1/session/:sessionId/launch

Payload: { "channelId": "dev" } 

Eventhough the "contentId" as well as "contentType" are optional, its not able to launch the app without these parameters and I want to launch only the app without deeplinking. In the above scenario, everytime I am getting a pop-up saying like the requested Content is not found. Can someone please help?