Update Identity User Claims in Web API

Main problem is that claim which represents user's name is not updated in ClaimsIdentity you are using in the last step.

The easiest way to perform the update is to use SignInManager<TUser, TKey>.SignIn method

signInManager.SignIn(identityUser, isPersistent: false, rememberBrowser: false);

This is also an ASP.NET Identity idiomatic way since it is using associated IClaimsIdentityFactory to create claims for new identities.

Complete example

static async Task<IdentityResult> UpdateEmailAsync<TUser>(    IPrincipal principal,    UserManager<TUser, string> userManager,    SignInManager<TUser, string> signInManager,    string newEmail)    where TUser : class, IUser<string>{    string userId = principal.Identity.GetUserId();    IdentityResult result = await userManager.SetEmailAsync(userId, newEmail);    if (result.Succeeded)    {        // automatically confirm user's email        string confirmationToken = await userManager.GenerateEmailConfirmationTokenAsync(userId);        result = await userManager.ConfirmEmailAsync(userId, confirmationToken);        if (result.Succeeded)        {            TUser user = await userManager.FindByIdAsync(userId);            if (user != null)            {                // update username                user.UserName = newEmail;                await userManager.UpdateAsync(user);                // creates new identity with updated user's name                await signInManager.SignInAsync(user, isPersistent: false, rememberBrowser: false);            }            // succeded            return result;        }    }    // failed    return result;}

Then you can just call it from your code

string newEmail = AntiXssEncoder.HtmlEncode(value.Email, true);IdentityResult result = await UpdateEmailAsync(identityUser, UserManager, SignInManager, newEmail);if (result.Succeeded){    return Ok();}