I have setup some feature services on ArcGIS online (My Content -> Add Item -> From the web) that point to our ArcGIS Server (10.2) endpoints. I checked “Store credentials with service item. Do not prompt for authentication.” as the ArcGIS Server services have token based security.
Using an ArcGIS 10.2.5 Runtime .net application I login via oAuth to the ArcGIS online and can add the features to the map without any problem.
If I then try and create a replica offline geodatabase from the application via the ArcGIS Online feature service endpoint it correctly creates the geodatabase on ArcGIS Server but before the callback method is invoked, the Esri code incorrectly prompts for an ArcGIS Server based token credential. Presumably this is done because the returned url to copy the geodatabase from is an ArcGIS Server url and not an ArcGIS Online url.
So how do you stop this happening as users would have to login to ArcGIS Online (via oAuth) and also have to login to ArcGIS Server if they create a replica geodatabase?