Hi, its an old post but i have same problem too.
i am using Arcgis server active directory authorization for securing rest services.
when i add a secured service to portal 10.6 i can see a login screen and i can use my active directory user credentials to see layer in my webmap.
But when i use that webmap in an application made with WAB developer edition and deploy my own server, i have that same error with blank white page just after seeing my basemap;
java.lang.NullPointerException: Input stream is null.
Redirected page adres. (cbs is my web adaptor name that same for server and portal side.yyy aplication foldername in wwwroot folder.):
https://xxx.xxx/cbs/tokens//home/signin.html?returnUrl=https%3A//xxx.xxx/yyy/
Also i get that error message with this page;
https://xxx.xxx/cbs/tokens//home/signin.html
We want to use our active directory user credentials to authorize rest service address for WAB web applications .
Thank you.
web appbuilder error arcgisserver arcgisportal rest service token #web-appbuilder
ArcGIS GIS Server Advanced 10.6
Arcgis Portal 10.6
WebApp Builder Developer Ed. 2.8
NonFederated Server-Portal