I have a Main project and a Model project in my solution. Main references Model. In Model there are resource PDF files in a folder called Manuals (in the base directory of the project) that are then opened in the default PDF reader app by a Main project script when a button is clicked. The script in Main looks like this:
using System.IO;
...
void OpenPDF(string filepath)
{
File.Open(filepath, FileMode.Open);
}
What does filepath look like?
Apologies for the lack of details, I am not quite sure what else you need to understand the problem. Comment if you need anything, I'll update the question.