Thanks for using our products.
Aspose.Pdf for .NET 2.1 is quite old release and till the release of latest version 5.4.0, there have been numerous improvements, lots of new features have been added and a bunch of issues have been fixed. We always recommend our customers to use the latest release versions and in case you encounter any problem or you have any further query, please feel free to contact. For complete details on features introduced and the issues fixed in this release, please check out Aspose.Pdf for .NET 5.4.0.
FYI, we recently have introduced a new Merged version of Aspose.Pdf for .NET 6.0.0 which includes the combined features of Aspose.Pdf for .NET and Aspose.Pdf.Kit for .NET. So now you can use the single product to generate and manipulate existing PDF documents. Please visit the following link for details on features introduced in Aspose.Pdf for .NET 6.0.0.