Hi,
1. There are no parameters in the dataset. I built the dataset in Visual Studio 2017 and deployed it from there. I also created a report that uses the same Shared Dataset and deployed it. When you run the report in the Web Portal, it opens and displays the correct data. I created a super simple dataset with just "Select getdate() as DateAndTime" and even that gives errors in the Web Portal when I try Data Preview and Load Data.
2. I have restarted the whole server. Behavior is exactly the same.
3. I have checked the logs and see no errors. I get the impression (thought I could be wrong) that it is a client-side error, something wrong with the web portal pages. I use IE normally, but get the same error in Chrome and Edge.
Kind Regards,
Etienne