Multipart Content-Type request results in IOException

RequestValidatorExtensions.cs

using Microsoft.AspNetCore.Builder;

namespace MvcBug
{
    public static class RequestValidatorExtensions
    {
        // Extensions method to simplify RequestValidatorMiddleware usage 
        public static IApplicationBuilder UseRequestValidator(this IApplicationBuilder app)
        {
            return app.UseMiddleware<RequestValidatorMiddleware>();
        }
    }
}

RequestValidatorMiddleware.cs

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

namespace MvcBug
{
    public class RequestValidatorMiddleware
    {
        private readonly RequestDelegate _next;

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

        public async Task Invoke(HttpContext context)
        {
            // Check if request body is empty and it's a multipart request
            if ((context.Request.ContentLength == null || context.Request.ContentLength == 0)
                && context.Request.ContentType != null
                && context.Request.ContentType.ToUpper().StartsWith("MULTIPART/"))
            {
                // Set 400 response with a message
                context.Response.StatusCode = StatusCodes.Status400BadRequest;
                await context.Response.WriteAsync("Multipart request body must not be empty.");
            }
            else
            {
                // All other requests continue the way down the pipeline
                await _next(context);
            }
        }
    }
}
// Blog post: https://ignas.me/tech/multipart-content-type-request-ioexception/ 

Startup.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Logging;
using Microsoft.Extensions.Options;

namespace MvcBug
{
    public class Startup
    {
        public Startup(IConfiguration configuration)
        {
            Configuration = configuration;
        }

        public IConfiguration Configuration { get; }

        // This method gets called by the runtime. Use this method to add services to the container.
        public void ConfigureServices(IServiceCollection services)
        {
            services.AddMvc();
        }

        // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
        public void Configure(IApplicationBuilder app, IHostingEnvironment env)
        {
            if (env.IsDevelopment())
            {
                app.UseDeveloperExceptionPage();
            }

            // Check for invalid HTTP requests before the MVC
            app.UseRequestValidator();
            // Let MVC process other requests
            app.UseMvc();
        }
    }
}