Routing in MVC, "Specify a root relative path with a leading '/'" - asp.net-mvc

Question

I had a razor page called Submit that was giving me a Value cannot be null. Parameter name : viewData error so I removed the #page at the top of my code as this post directed. My issue now is that when I load the page I the following error:
InvalidOperationException: The relative page path 'Index' can only be used while executing a Razor Page. Specify a root relative path with a leading '/' to generate a URL outside of a Razor Page. If you are using LinkGenerator then you must provide the current HttpContext to use relative pages.>
I want my page to have a URL of https://localhost:44369/Submit How would I do this? Here is my routing in my Startup.cs file:
app.UseMvc(routes =>
{
routes.MapRoute("default", "{controller=Home}/{action=Index}/{id?}");
});

Answer 1

The reason you are getting the error is because of incorrect syntax. In one of your Razor Views, you probably have an anchor tag that might look like:
<a asp-page="Index">Index</a>
That syntax (without the forward slash /)is meant for a Razor Page. In the Razor View, prefix the Page name with a forward slash:
<a asp-page="/Index">Index</a>
If everything else is correct you should be able to browse https://localhost:44369/Submit and it should show the whatever is written in your Submit page

Answer 2

You might use Razor Pages asp-action in a MVC project.
For MVC
1> Using tag asp-action but not asp-page to redirect.
<a asp-action="Submit" class="btn btn-success form-control">Submit</a>
2> use Route Attribute to route to the specified view .
Controller.cs
public class HomeController : Controller
{
[Route("/Submit")]
public IActionResult Submit()
{
return View("~/Views/Home/Submit.cshtml");
}
}
Test:
https://localhost:44307/Submit
https://localhost:44307/submit
The screenshot of result:
There are some articles it might help you to figure out Razor Pages and MVC.
How Does Razor Pages Differ From MVC In ASP.NET Core?
Building Your .NET App - Razor Pages vs. ASP.NET MVC