Hi all umbracians,

I'm trying to open an issue at http://issues.umbraco.org, but it appears that youtrack application isn't collaborating... as today.

Nevertheless I've tried to follow the instructions of the documentation regarding extending umbraco backoffice security by implementing a custom IBackOfficeUserPasswordChecker. Although I've already tried the exact same code that is suggested in a 7.8.3 version and in a clean latest version 7.11, but also returns the same error:

Unable to cast object of type 'System.Security.Claims.ClaimsIdentity' to type 'Umbraco.Core.Security.UmbracoBackOfficeIdentity'

My current implementation at the 'UmbracoCustomOwinStartup' class:

public void Configuration(IAppBuilder app) {

        var applicationContext = ApplicationContext.Current;
        app.ConfigureUserManagerForUmbracoBackOffice<BackOfficeUserManager, BackOfficeIdentityUser>(
            applicationContext,
            (options, context) =>
            {
                var membershipProvider = Umbraco.Core.Security.MembershipProviderExtensions.GetUsersMembershipProvider().AsUmbracoMembershipProvider();
                var store = new BackOfficeUserStore(
                            applicationContext.Services.UserService,
                            applicationContext.Services.EntityService,
                            applicationContext.Services.ExternalLoginService,
                            membershipProvider);
                var userManager = new BackOfficeUserManager(store)
                {
                    //Set your own custom IBackOfficeUserPasswordChecker
                    BackOfficeUserPasswordChecker = new MyPasswordChecker()
                };
                return userManager;
            });


        //Ensure owin is configured for Umbraco back office authentication
        app
            .UseUmbracoBackOfficeCookieAuthentication(ApplicationContext.Current)
            .UseUmbracoBackOfficeExternalCookieAuthentication(ApplicationContext.Current);
    }

And the MyPasswordChecker class:

internal class MyPasswordChecker : IBackOfficeUserPasswordChecker
    {
        public Task<BackOfficeUserPasswordCheckerResult> CheckPasswordAsync(BackOfficeIdentityUser user, string password)
        {
            var result = (password == "test")
                ? Task.FromResult(BackOfficeUserPasswordCheckerResult.FallbackToDefaultChecker)
                : Task.FromResult(BackOfficeUserPasswordCheckerResult.InvalidCredentials);

            return Task.FromResult(BackOfficeUserPasswordCheckerResult.ValidCredentials);
        }
    }

Maybe is something that I'm missing? Anyone had this issue before?