Hi everyone,
I have a custom board based on nrf52840, the Fantsel BC840. I have created my custom board, changing assigment of pins for leds, buttons and UART0 on custom_board.dts


All work fine but i have the next issue... When i try to send a shell command using UART0 shell isn't react, and get this warning:

How i can active shell backend to fix this error???
Any help is welcome, regards.