CustomSwitches don't work in .netCore 3.1

[willpower18]

I use the rotativa .net Core 1.2.0 Beta Version in .NetCore 3.1 application, and te Custom Switches parameter not work. It Crashes with 500 Error.

I have the code:

string footer = "--footer-right [page]";

            var rel = new ViewAsPdf("Print")
            {
                PageOrientation = Rotativa.AspNetCore.Options.Orientation.Portrait,
                PageSize = Rotativa.AspNetCore.Options.Size.A4,
                PageMargins = { Left = 10, Right = 10 },
                Model = model,
                CustomSwitches = footer,
            };
            return View(rel);