ASP.NET Core redirecting to the same page after submitting a form with HttpPost method

please replace this

 <form asp-controller="NewOrder" asp-action="CreateOrder" class="well">

with

   <form asp-controller="NewOrder" asp-action="NewOrder" class="well">

you are using asp-action="CreateOrder" thats why it is going to CreateOrder method

try this return RedirectToAction("ActionMethod", "Controller");