Power BI Embedding Error In Downloaded Sample

Hi Team,

I used the below sample solution to embed a report. I have entered the client id , group Id , report Id and also my credetials in the web config. 

I have also granted permissions to the app in the setting section/required permission for the Power BI service.

Power BI Sample

Couldnt find any documentation on this error.

Help Required to resolve this.

Regards

Malcolm