Startup.cs

using DevExpress.AspNetCore;
using DevExpress.AspNetCore.Reporting;
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;

namespace SimpleAspNetCoreReportingViewer {
    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();
            services.AddDevExpressControls();


            services.ConfigureReportingServices(configurator => {
                configurator.ConfigureReportDesigner(designerConfigurator => {
                    designerConfigurator.RegisterDataSourceWizardConfigFileConnectionStringsProvider();
                });
                configurator.ConfigureWebDocumentViewer(viewerConfigurator => {
                    viewerConfigurator.UseCachedReportSourceBuilder();
                });
            });
        }

        // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
        public void Configure(IApplicationBuilder app, IWebHostEnvironment env) {
            app.UseDevExpressControls();
            System.Net.ServicePointManager.SecurityProtocol |= System.Net.SecurityProtocolType.Tls12;
            if (env.IsDevelopment()) {
                app.UseDeveloperExceptionPage();
            }
            app.UseStaticFiles();
            app.UseRouting();
            app.UseEndpoints(configure => {
                configure.MapDefaultControllerRoute();
            });
        }
    }
}