System.InvalidOperationException: C#

Question

I'm using the Aspose lib to convert a PDF file to Excel file, my code below:

using Aspose.Pdf;

public async Task convertPDFtoEXCEL(Document pdfFile, string root, string fileName)
{
    // Initialize ExcelSaveOptions
    ExcelSaveOptions opts = new ExcelSaveOptions();

    // Set output Excel XLSX format
    opts.Format = ExcelSaveOptions.ExcelFormat.XLSX;

    // Minimize number of Worksheets
    opts.MinimizeTheNumberOfWorksheets = true;

    // Convert PDF to Excel output file
    pdfFile.Save(root + fileName + ".xlsx", opts);
}

public async Task<int> Get()
{
    int number = 0;
    string root = "C:/Users/Downloads/";
    string fileName = "myFile";

    // load the PDF file                    
    Document pdfFile = new Document(root + fileName + ".pdf");

    // convert the PDF file to EXCEL
    await convertPDFtoEXCEL(pdfFile, root, fileName);

    // ...
    return number;
}

When my code ran I got this error:

System.InvalidOperationException: 'A model description could not be created. Duplicate model name 'Element' was found for types 'Aspose.Pdf.Structure.Element' and 'Aspose.Pdf.LogicalStructure.Element'. Use the [ModelName] attribute to change the model name for at least one of the types so that it has a unique name.'

What is the problem, and how can I fix it?