Replied 8 September 2017, 3:00 pm EST
I would like you to know that the OpenSpreadFile method is used to open Spread Com files in the .Net environment. To open an xml file saved from Spread designer you should use the Open method of the FpSpread class i.e used to open a saved xml stream. I tried to open both these xml files, one generated from the Spread designer and the other one that you expanded, using the Open method of the FpSpread class and both the files were opened without any issues. Here is the code to use for the same:
You can refer to the following link for more details about the Open method:
Hope it will help you. Please let me know if you have any queries further.