ASP.NET Identity username won't refresh after signout/signin

Question

We are using ASP.NET Identity 2.0, and want to allow username change. When it is changed, the following happens:

1. user is signed out => no error
2. username is changed in database => works, the change is visible
3. user is signed in with new username => works but still shows old username

The problem is step 3, after signin the user is still returned with the old username, even though in the db it's the new one, and login with the new one worked.

I tried the following to clear existing references:

Context.GetOwinContext().Authentication.SignOut(); // also tried it with DefaultAuthenticationTypes.ExternalCookie
Session.Clear();
Session.Abandon();

// sign in with the new username => no problem
IdentityHelper.SignIn(manager, user, false);

// added this later, when the rest didn't work, but didn't help either
Context.User = new System.Security.Principal.GenericPrincipal(new System.Security.Principal.GenericIdentity(user.UserName), roles);

// tried this too, but didn't help either
System.Web.Security.FormsAuthentication.SetAuthCookie(user.UserName, true);

// after executing the following statement, user always has the old username
var user = Context.User.Identity.GetUserName();

All statements execute without error. Any ideas what else needs doing?

EDIT

Also tried clearing the cache via loop

foreach (System.Collections.DictionaryEntry entry in HttpContext.Current.Cache)
    HttpContext.Current.Cache.Remove(entry.Key as string);

and also Context.Application.Clear();

Also tried wiping the user, i.e 'Context.User = null' but this resulted in an exception on signIn. When I execute 'user = manager.Find("newUserName", password)' to sign in with, it returns the user but even though it was retrieved with the new username, it still actually contains the old username. Not sure what else I should clear.

Answer 1

Also posting this answer because I was tearing my hair out :)

I tried everything even the redirect as listed above. However I came across this article http://benfoster.io/blog/aspnet-identity-stripped-bare-mvc-part-2 and noticed that he was using the signout except he was specifying the type so

_applicationSignInManager.AuthenticationManager.SignOut("ApplicationCookie") 

instead of leaving it blank, I tried it at it worked! without the redirect.

So my code looks like this-

_applicationSignInManager.AuthenticationManager.SignOut("ApplicationCookie");
FormsAuthentication.SignOut(); // doing for good measure (might not need)

// Sign back in (Does the password sign in etc)
var resultSignIn = helper.PasswordSignIn(userName: userName, password: password, isPersistent: false, shouldLockout: true);

// Update the HttpContext with the new user
HttpContext.Current.User = new GenericPrincipal(new GenericIdentity(userName), new string[] { });

Answer 2

Posting this as an answer in case someone else pulls their hair out over this. Turns out a redirect does solve the problem, but it needs to be done in between signOut and signIn.

If the redirect happens after signIn, as I had tried before, the old value is retained. So somehow something seems to be cleared during redirect that I wasn't able to remove manually but which needs clearing before signing in again.