multiple definition of g_pfnVectors Posted by mike796 on 2017-07-20 15:27 Hi, I got the problem, you probably have twice the startup file in your env : MCT_OLED_Display/Libraries/CMSIS/device/startup_stm32f303xe_ac6.s startup/startup_stm32f303xe.s If this is the case you should remove one from your env.