Tag helpers not creating proper URL

Tag Helpers enable server-side code to participate in creating and rendering HTML elements in Razor files. There are many built-in Tag Helpers for common tasks - such as creating forms, links, image version number.
We are going to solve the issue that URL is not generated properly. There are several things to check:

Import tag helper correctly

In the _ViewImports.cshtml file, import tag helper as follow.

@addTagHelper *, Microsoft.AspNetCore.Mvc.TagHelpers

Notice: _ViewImports.cshtml should under the "Views" folder, since it works only for files in the "Views" directory or sub-directory.

Include tag helper in dependencies

Make sure "Microsoft.AspNetCore.Mvc.TagHelpers" is referred in the dependencies folder in Nuget.

Check self-defined routes in Startup.cs

Check the routes whether the codes in .cshtml files is consist with the template route.

For example in my case, my route is :

Startup.cs:

app.UseMvc(routes =>
            {
                routes.MapRoute("default", "{controller=home}/{action=index}/{id?}");
            });

When using tag helper for generate link, codes are like this in _Layout.cshtml :

<ul class="navbar-nav">
    <li class="nav-item">
       <a asp-action="index" asp-controller="home" class="nav-link">List</a>
    </li>
    <li class="nav-item">
       <a asp-action="create" asp-controller="home" class="nav-link">Create</a>
    </li>
</ul>

Then the links are generated :

 <div class="collapse navbar-collapse" id="collapseNabar">
      <ul class="navbar-nav">
            <li class="nav-item">
                <a class="nav-link" href="/">List</a>
            </li>
            <li class="nav-item">
                <a class="nav-link" href="/home/create">Create</a>
            </li>
      </ul>
</div>

Notice: If you only use app.UseMvc() in the Startup.cs, without a route defination. There might have issues, such as links are not generated. This is because you didn't give a template for routes, tag helper only return a "" as the value of href.

Check Attribute routing

Strange results occur when you define both self-defined routes in Startup.cs and attribute routing in controller. Try to use self-defined routes in Startup.cs only when using tag helper, or use app.UseMvc() + attribute routing in controller.

HomeController:

[Route("")]   // delete these attribute routing when use self-defined routes
[Route("Home")]
[Route("Home/Index")] 
public ViewResult Index()
{
    var model = _employeeRepository.GetAllEmployee();
    return View(model);
}

public void Configure(IApplicationBuilder app, IHostingEnvironment env)
        {
            if (env.IsDevelopment())
            {
                app.UseDeveloperExceptionPage();
            }
            app.UseStaticFiles();
            app.UseMvc();
        }

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