Invalid command '<command>' for file type '<filetype>'
The Command property for the specified file type is not an executable file or a project output that results in an executable file. The Command property specifies the executable file that is launched when an action is invoked on a file type; files that are not executable files cannot be launched.
To correct this error
Double-click the error in the Task List to go to the referenced file type in the File Types Editor.
In the Properties window, select the Command property. Click the ellipsis (...) button to open the Select Item in Project dialog box.
Choose a folder that contains the executable file for the file type, and select the executable file.