public async Task OnGetAsync(string returnUrl = null) { if (!string.IsNullOrEmpty(ErrorMessage)) { ModelState.AddModelError(string.Empty, ErrorMessage); } returnUrl = returnUrl ?? Url.Content("~/"); // Clear the existing external cookie to ensure a clean login process await HttpContext.SignOutAsync(IdentityConstants.ExternalScheme); ExternalLogins = (await _signInManager.GetExternalAuthenticationSchemesAsync()).ToList(); ReturnUrl = returnUrl ?? Url.Content("~/"); TempData["ReturnUrl"] = ReturnUrl; }