asp-action behave differently between ASP.NET Core 2.2 and 3.1 when Action Method has Async suffix

[TheBlueSky]

While upgrading an application from ASP.NET Core 2.2 to 3.1 I noticed that asp-action TagHelper behave differently in these versions.

I am not sure this is intentional or not, or whether it was announced as a breaking change or not. Also, not sure if this issue is talking about the same thing or not; in my case, the link is not generated at all.

Describe the bug

In ASP.NET Core 2.2, when using the Action Method name with asp-action TagHelper, the link is generated as expected. However, in ASP.NET Core 3.1, no link is generated if the Action Method has Async suffix.

For more details, see "To Reproduce" section.

To Reproduce

1. Create an ASP.NET Core 2.2 Razor Pages application.
2. Add the Controller code; see Controller code below.
3. Add a link in Index.cshtml; see HTML code below.
4. Run the application and see that the link is generated correctly for /Account/Logout.

// Controller code
public sealed class AccountController : Controller
{
    [Route("/Logout")]
    public async Task<IActionResult> LogoutAsync()
    {
        await this.HttpContext.SignOutAsync(CookieAuthenticationDefaults.AuthenticationScheme);

        return this.RedirectToPage(ApplicationConstants.IndexPage);
    }
}

<!-- HTML code -->
<a asp-controller="Account" asp-action="LogoutAsync">Logout</a>

Repeat the same steps, but now create an ASP.NET Core 3.1. Run the application and see that there is no link generated and the rendered anchor tag is:

<a href="">Logout</a>

Lastly, remove Async from asp-action TagHelper:

<!-- HTML code -->
<a asp-controller="Account" asp-action="Logout">Logout</a>

Run the application and see that the link is generated as expected.

[pranavkm]

@TheBlueSky see https://docs.microsoft.com/en-us/aspnet/core/migration/22-to-30?view=aspnetcore-3.1&tabs=visual-studio#async-suffix-removal-from-controller-action-names, dotnet/docs#14716

[TheBlueSky]

Thanks, Pranav; I should have completed the document until the end I guess :p