Printing html to pdf using Pechkin (WkHtmlToPdf) is not working

Question

I have a serious problem with Pechkin (WkHtmlToPdf).
After converting an html string to pdf for n-times, it won't work anymore.

Does anybody know how can I fix the problem?

Here is my code:

public static byte[] HtmlToPdf(string html)
{
    // Create global configuration object
    var gc = new GlobalConfig();

    // A new instance of Margins with x-inch margins.
    gc.SetMargins(new Margins(20, 20, 20, 20))
        .SetPaperSize(PaperKind.A4);

    var pechkin = new SimplePechkin(gc);
    var configuration = new ObjectConfig();

    // Generate the PDF with the given configuration
    var pdfContent = pechkin.Convert(configuration, html);
    pechkin.Dispose();

    return pdfContent;
}

In the caller method:

var html = "Hi there!";
var pdf = PdfHelper.HtmlToPdf(html);

PdfHelper.DownloadAsPdfFile("MyFileName", pdf);

Actually after n-times print, the program is stopped in Convert line:
var pdfContent = pechkin.Convert(configuration, html);

Any help would be much appreciated.