Custom Bootloader and UART

[JThom.15]

Hello,

I'm using an STM32F205 chip with custom bootloader. I am facing an issue, that when main application is loaded through the bootloader some of the uart's (USART6 and UART4) interrupt transmit (HAL_UART_Transmit_IT()) causes the stm32 to crash. Other Uart's are working fine. 
If I load the main application without bootloader all the Uarts works without any issue. Are there any ideas about peripherals behavior in application after the jump from a bootloader? Any help would be much appreciated 

Thanks 

[TDK]

Perhaps they are not in a reset state, causing undesired behavior. Debug the code, figure out what "crash" here means in particular and solve it. This is a likely a software bug/issue.