Sending a form POST HTTP request (Content-Type: application/x-www-form-urlencoded) to the below controller results into a HTTP 415 Unsupported Media Type response.

public class MyController : Controller
{
    [HttpPost]
    public async Task<IActionResult> Submit([FromBody] MyModel model)
    {
        //...
    }
}

Form post HTTP headers:

POST /submit HTTP/1.1
Host: example.com:1337
Connection: keep-alive
Content-Length: 219
Pragma: no-cache
Cache-Control: no-cache
Origin: https://example.com:1337
Upgrade-Insecure-Requests: 1
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/58.0.3029.110 Safari/537.36
Content-Type: application/x-www-form-urlencoded
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8
Referer: https://example.com:1337/submit
Accept-Encoding: gzip, deflate, br
Accept-Language: en-US,en;q=0.8,nl;q=0.6

This used to work with ASP.NET MVC 5 on .NET 4.6.