Maple mini and STM32 MCU Based boards problem

I have a problem after programing STM32F103 boards.
I Installed "STM32 MCU Based boards" because STM32LowPower library need that. But when I upload codes into board maple mini port is not accessible . what is solution for that ?
My Arduino setting before and after uploading code:

after uploading code I can not access the serial monitor

What board are you using? Could you post a picture?

Hi ,
Thank you for your response.
I use black pill stm32 board :

I have not had any problems with this before when I used Arduino_STM32 (stm32duino core). But since I installed the new kernel (stm32 MCU based boards core ), after uploading the codes on the board, I no longer have a serial connection.

Your sketch probably ran amok and overwrote the bootloader. Either that, or the kernel you used doesn't support USB serial. You have to re-install a working DFU bootloader. Get yourself an ST-Link programmer...

Another thing, if you want application (sketch) USB serial support, you have to ensure that it is selected in the upload menus... however it appears like you do.