In general, I am able to use Denodo from VisualStudio and C# with Npgsql data provider.
Based on the information provided [here](https://github.com/npgsql/Npgsql.EntityFrameworkCore.PostgreSQL/issues/382), the error message “Received unexpected backend message ParseComplete. Please file a bug” seems to be related to Npgsql.
For your scenario, I would have a look at the vdp log file located at
"<DENODO_HOME>\logs\vdp\vdp.log" to get more information on the issue.
Hope this helps!