There is a reason why remoteError is not returned to login view?

[PiemP]

Good day to everyone,

I'm looking to create a module that allow user to authenticate by using a custom system. I can intercept an authentication failed event but I can't retrieve the returnUrl parameter. I believe that I can retrieve it by redirecting the user to the ExtenalLoginCallback function in the AccountController class of the OrchardCore.Users module. To this redirect I would attach a message to explain what are goes wrong but the function return a generic message in all the cases.

Why if I send a remoteError message to ExternalLoginCallback it is logged but is never return to the view?

Another question is: why implementing IExternalLoginEventHandler the function UpdateRoles is called every time user login? Is not better to call it only at the end of an user registration?

Probably I do something wrong. I would like to compile some CustomUserSettings, after user registration, by taking data from the claims returned by the authentication system.

Thank you.