Hi,
I regret for the delayed response.
Could you please check the following?
1) Reference the interop assemblies "AxSHDocVw.dll and SHDocVw.dll" assembly to the project in addition to Syncfusion.Pdf.base.dll and Syncfusion.HtmlConverter.base.dll
2) Add the below page directive to provide COM interoperability in ASP .NET environment.
@Page directive AspCompat="true".
And also, kindly refer the below link to get more details for converting html to PDF:
http://www.syncfusion.com/products/pdf/windows/Articles/Html_To_PDF.aspxPlease follow the steps that is mentioned in the above link and let us know if the issue still exists.
Thanks,
Melba