The pages are missing for the CodeBehind files. The project file cannot find the Aspose.Project reference as well; need to remove and add, likely a wrong path is set. Please look into this.
Dear BlahBlah,
Sorry, I didn’t set reference to the Aspose.Project.dll correctly.
I included correct demos to the new installer, please download it and reinstall Aspose.Project.
https://releases.aspose.com/tasks/net/
Thanks for your consideration.