WAB GP Widget Error: User cannot be identified and hence cannot create output feature service.

[elmort]

I wrote a custom Python script tool and published it to my ArcGIS Enterprise portal as a Web Tool. I am now trying to consume the tool in WebApp Builder via the Geoprocessing Widget, but received the following error: 

“Submitted.
Executing…
User cannot be identified and hence cannot create output feature service.
Failed.”

I am signed in on our Portal as a Publisher with additional permissions, so I should have permission to create Feature Services. Has anyone encountered this error before? and if so, what does it mean, and how can I resolve it? 

[JackChen4]

From the Portal, please limit the published Web Tool access permission to owner and/or group only. You must login to access your Web Map Application.