Power Query Online + SAP BW Application Server: Exception Error

This is a huge question, and likely impossible for me to give a direct answer to. Without being able to see exactly what you're seeing, it's really hard to understand what might be causing you these issues to be honest. A lot will depend on your local tech/infrastructure, so you may need to check things like:

-1- Which provider version does your SAP App Server require? Does it always demand the latest version, or do you have to match the provider version to the DB version?

-2- Do you need to run your exernal connections through a proxy server to get through the firewall? If so, you may need to update the proxy values in the following gateway config files:

--- EnterpriseGatewayConfigurator.exe

--- Microsoft.Mashup.Container.NetFX45.exe

--- Microsoft.PowerBI.EnterpriseGateway.exe

-3- Have you correctly added your App Server as a new source on the gateway(s) in the PBI Service? Have you then updated the dataset of any report using this source with the gateway source?

Sorry I can't be of more help here. I myself have always found gateways the most fiddly and frustrating part of setting up any PBI infrastructure, especially when dealing with external Drivers/Providers. I still have nightmares about an old Oracle server I had to connect to where it turned out the provider would only run on Windows 7, so I had to set up a Win7 gateway just for that source! Brrrrrr 😖

Pete