Comment out the apiUrl in the following areas:<a href="file:C:/Program" target="_blank">C:\Program</a> Files\ArcGIS\Portal\apps\webappviewer\env.js (2D WAB viewer)<a href="file:C:/Program" target="_blank">C:\Program</a> Files\ArcGIS\Portal\apps\webappbuilder\stemapp\env.js (configurator of 2D WAB)<a href="file:C:/Program" target="_blank">C:\Program</a> Files\ArcGIS\Portal\apps\webappbuilder\stemapp3d\env.js (configurator of 3D WAB)<a href="file:C:/Program" target="_blank">C:\Program</a> Files\ArcGIS\Portal\apps\webappviewer3d\env.js (3D WAB viewer)However, once Portal for ArcGIS is re-started, the apiUrl is uncommented again.