When I set up the Umbraco runtime to 'production', the custom Error controller I have in place to display the 500 errors is not hit.

The controller is just this.

[Route("Error")]
public class ErrorController : Controller
{
    public IActionResult Index()
    {            
        return View("Index");

    }
}

This is my Startup.cs

public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
    {
        if (env.IsDevelopment() || env.EnvironmentName == "Int")
        {            
            app.UseDeveloperExceptionPage();
        }
        else
        {
            app.UseExceptionHandler("/Error");
            app.UseHsts();
        }

        app.UseHttpsRedirection();
        app.Use(async (context, next) =>
        {
            context.Response.Headers.Add("X-Frame-Options", "SAMEORIGIN");
            context.Response.Headers.Add("X-Content-Type-Options", "nosniff");
            context.Response.Headers.Add("X-XSS-Protection", "1; mode=block");
            await next();
        });

        app.UseMvc(routeBuilder =>
        {
            routeBuilder.Expand().Select().Filter().OrderBy().MaxTop(100).Count().SetTimeZoneInfo(TimeZoneInfo.Utc);
            routeBuilder.MapRestier(u =>
            {
                u.MapApiRoute<AcpccApi>("ApiV1", "dataApi", true);
            });
            routeBuilder.EnableDependencyInjection();

        });
        app.UseRouting();
        app.UseUmbraco()
            .WithMiddleware(u =>
            {
                u.UseBackOffice();
                u.UseWebsite();
            })
            .WithEndpoints(u =>
            {
                u.UseInstallerEndpoints();
                u.UseBackOfficeEndpoints();
                u.UseWebsiteEndpoints();
            });
    }

If I remove the runtime setting from appsettings.json, the custom error is displayed.