From the documentation:
Creating an extension using only Visual Studio
4 To be able to debug the extension, you must manually do the following configuration in Visual Studio:
Select the extension project in Solution Explorer.
Select View > Property Pages .
On the Debug page, click Open debug launch profiles UI, and, in the Launch Profiles dialog, do the following:
Click Create a new profile , and choose Executable.
For your new profile, under Executable, point to a Spotfire.Dxp.exe on your computer. It could be your installed version, some intermediate beta-version or similar. For example, C:\Users\{username}\AppData\Local\Spotfire\14.0.0\Spotfire.Dxp.exe.
Is it mandatory to use 14.0.0\Spotifre.Dxp.exe to execute Extenstion examples of \..\SPOT_sfire_dev_14.2.0_win\SDK\Examples\Extensions\SpotfireDeveloper.CustomPanelExample
or we can point to older executables?