The question at https://community.st.com/s/question/0D50X00009XkeGq/what-usarts-can-be-used-for-boot-on-64pin-stm32f401rct6-stm32f401xbc?t=1576434345679 was left unanswered. The words "The USART2 uses its remapped pins" in AN2606 gives the impression...