It looks like the latest version of the .NET 4.0 DLL includes a definition for the ExtensionAttribute System Class. System.Runtime.CompilerServices.ExtensionAttribute. This is causing a compile error. Is a definition for this class supposed to be included in a .NET 4.0 version of the Aspose.BarCode.dll?
On further research, it looks like this is a way to get extension methods to work in .NET 2.0 but isn’t needed for 4.0.
Attached is a zipped solution that demonstrates the problem.
We use extension methods in our code, so I have included two in the project. If the body of the extension classes are commented out, the project compiles fine. If they not (so extension methods are compiled) then the project will not compile. If the reference to Aspose.BarCode.dll is removed, the project also compiles.
It looks like the inclusion of System.Runtime.CompilerServices.ExtensionAttribute in the Aspose.BarCode.dll compiled for .NET 4.0 is what is causing the problem. I don’t believe this is needed in 4.0.