I’m updating to a new version of aspose.net in an existing project to fix a bug with opening files created in newer versions of excel, the process has been mostly straight forward, a few changes to account for some changes to the way styles are set but nothing major.
I think you are using the wrong dll of Aspose.Cells. When you use our product in a a web application, please use the Aspose.Cells.dll from the net2.0 folder in the “/bin” directory. I think you are using the ClientProfile version of Aspose.Cells Assembly. For your information, the dll in net3.5_ClientProfile directory is used only for the console application with Net frame client profile as the target framework of vs.net, you cannot use this dll in a web project. Please check your project, it is possible that your project is referencing this dll. For complete reference, please read the “readme.txt” file in the bin directory (when you install Aspose.Cells for .NET v7.0.1 using its msi installer).
Moreover, please check the document for your complete reference:
(Note: see the description/example codes under “3. Saving file to Response Object” sub-topic)
Let us know if you still have any confusion.