Unable to connect to STM32l4R5 bootloaader

[VVerm.0]

I am using stm32l4r5zit6 dev board, and i have invoked the bootloader from the ROM but the stm32 flasher is not able to connect to the bootloader via uart.

[TDK]

Make sure you reset it with BOOT0 pulled high in order to enter bootloader mode. You don't say how you "invoked the bootloader".

[VVerm.0]

yes that is exactly what i did to enter the bootloader mode. The application code in flash stopped after reset with BOOT0 pin high. But the STM32 flasher couldn't communicate with it .