Embedding a report in a simple ASP.NET application

Hi,

I'm trying to setup a very asp.net application (following https://docs.microsoft.com/en-us/sql/reporting-services/application-integration/integrating-reporting-services-using-reportviewer-controls-get-started?view=sql-server-2017).

Everything is running on my local machine (SRRS, SQLServer...). I managed to make SSRS2017 runs and created a couple of reports.

When I try to access to the page, I have this simple message " The request failed with an empty response" and the browser console shows the following message

Failed to load resource: the server responded with a status of 500 (Internal Server Error)

http://localhost:24947/Reserved.ReportViewerWebControl.axd?OpType=SessionKeepAlive&ControlID=ef5d4135d9724795bd91be8d6ec3f1cd&RSProxy=http%3a%2f%2flocalhost%3a8989%2freports_portal

When I open the page it shows "OK"

Any help will be appreciated

Thanks