EnableBufferingMiddleware.cs

using System.IO;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.Http.Features;

namespace YourNamespace
{
	public static class HttpRequestExtensions
	{
		public static bool CanReadBody(this HttpRequest request)
		{
			return (
				       request.Method == HttpMethods.Post
				       || request.Method == HttpMethods.Put
			       )
			       && request.Body.CanRead;
		}
	}
	
	public class EnableBufferingMiddleware
	{
		private readonly RequestDelegate _next;

		public EnableBufferingMiddleware(
			RequestDelegate next
		)
		{
			_next = next;
		}

		public async Task InvokeAsync(HttpContext context)
		{
			var request = context.Request;
			if (request.CanReadBody())
			{
				request.EnableBuffering();
			}

			await _next(context);
		}
	}
}