UseExceptionHandler not work in netcore3 preview7

create a new project ,nothing changed.

And I manual throw an exception in an action.

app.UseExceptionHandler("/Home/Error");

it is worked in netcore2.2，but failed in netcore3 preview7.

when I use this code, it is worked.

app.UseExceptionHandler(builder =>
            {
                builder.Run(async context =>
                {
                    context.Response.Redirect("/Home/Error");
                });
            });

I can't understand...