while CubeProgrammer connect to UART interface Error: Activating device: KO. Please, verify the boot mode configuration and check the serial port configuration. Reset your device then try again...

[ssah.1]

..

[Tesla DeLorean]

You get one shot at connecting at each reset. So might need to cycle and try again​, making sure BOOT0 is HIGH.

​

Perhaps provide more context about your situation, board and STM32 part. That will require less psychic energy on everyone else's part.

[KDJEM.1]

Hello @ssah.1​ and welcome to the Community :),

Which STM32 product you are using?

I advise you, when you configured the bootloader, to refer at this AN2606 "STM32 microcontroller system memory boot mode" and get inspired form the steps described in this MOOC"STM32 boot and startup tips - 2 Embedded bootloader investigations".

I hope this help you!

Kaouthar