@valon_hoti_gmail_com be aware that in the STM32Fx_Startup.cpp in function STM32Fx_Startup_GetDebuggerTransportApi() code there’s a bug:
…
#elif defined(DEBUGGER_FORCE_API) && defined(DEBUGGER_FORCE_INDEX)
api = DEBUGGER_FORCE_API;
#else
But need to set:
#elif defined(DEBUGGER_FORCE_API) && defined(DEBUGGER_FORCE_INDEX) api = DEBUGGER_FORCE_API; configuration = (const void*)&STM32F4_Startup_UsbDebuggerConfiguration; #else
otherwise the UDB Debugger configuration struct is never initialized, mostly crashing firmware.