Hello, I have a working program running on STM32F072R8 CPU that works with external device and gets data via external interrupt (EXTI4_15_IRQHandler function). The collected data is forwarded later via USB port to computer. Recently I started a modification in order to implement firmware update using custom boot-loader. I successfully implemented both boot-loader and main module based on the IAP sample project. The problem is that USB and timer IRQ still work, but the program gets no EXTI4_15_IRQHandler call anymore. Only if I run it with J-Link debugger, the program gets the external interrupt. Or if I revert the code to run from usual memory location (without boot-loader). How can I solve the problem?