Solved
Including FATFS with CubeMX breaks everything.
Using an stm32f105RBt6 :
- i have a working project with canbus and USBdevice.
- i have another working project with canbus and FAtFS(SPI-sd card)
None of them work once i include FATfs+USBCDCdevice
i dont know what to make up from this, last time i had a similar error i had messed up my include logic.

stm32f105RBt6 custom board.- SD Card trough SPI2, sandisk ultra 16GB.
- CubeMx version 6.4.0, STM32Cube_FW_F1_V1.8.4 package which uses FatFs version R0.10c, Nov 09, 2014.
- CubeIDE Version: 1.8.0
