Hello Bernard,
I suppose you have used (imported) an existing project in KDS 3.0.0 and you executed the Build operation.
In the main menu, open Project > KDS Upgrade Assistant, select the project and click on the Next.
The following options with descriptions are displayed in the KDS Upgrade Assistant for updating of your project:

You need to add the implementation of exit.c function.
Best Regards,
Marek Neuzil