Hi, any feedback on this?
I have the same problem. Is it a bug of 10.4?
I am using the esri proxy to pass the credential to the portal!
Fabio, you don't need to repost (i.e. make a duplicate post) to allow other groups to see you post...i.e. get ore exposure. I suggest deleting this one, then edit your other post while tagging this group like Web AppBuilder for ArcGIS that way, comments will remain in one thread. You can also move it here and tag ethe other group if you think that is more appropriate.
I'll go add a comment on the other with some links. I'm working on updating my proxy right now myself.