public async Task <IActionResult> LinkLoginCallback() { var user = await _userManager.GetUserAsync(User); if (user == null) { throw new ApplicationException($"Unable to load user with ID '{_userManager.GetUserId(User)}'."); } var info = await _signInManager.GetExternalLoginInfoAsync(user.Id); if (info == null) { throw new ApplicationException($"Unexpected error occurred loading external login info for user with ID '{user.Id}'."); } var result = await _userManager.AddLoginAsync(user, info); if (!result.Succeeded) { throw new ApplicationException($"Unexpected error occurred adding external login for user with ID '{user.Id}'."); } // Clear the existing external cookie to ensure a clean login process await HttpContext.SignOutAsync(IdentityConstants.ExternalScheme); StatusMessage = "The external login was added."; return(RedirectToAction(nameof(ExternalLogins))); }