Hi,
Thanks for your posting and using Aspose.Cells.
We have looked into your code and it looks fine. Are you getting this problem with specific excel file or with all excel files. Please share a sample console application project with us causing this exception. We will look into it and help you asap.
Please also provide us the source excel file(s) used in your code for our investigation.
You may also download and give a try to latest version
<a href="https://forum.aspose.com/t/36555">Aspose.Cells
for .NET v8.6.3.5</a>
to see if it makes any difference.<br><br>