This Error indicates an attempt to flash a project to the board while a Debug Session is still running. Only one project can be debugged or run at the same time.
From the debug perspective, make sure all sessions are terminated before deploying a new project. i.e:
Toolbar Menu > Window > Open Perspective > Debug
It is important to verify that there are no open debug sessions running before Running/Debugging a new project
For more complete information about compiler optimizations, see our Optimization Notice.