irrelevant information on serial port when I jump into FLASH APP using my IAP?

[fujiangmu]

[TDK]

My guess is your application writes to UART1 as well.

Nothing wrong that would explain this in the code you've shown.

[fujiangmu]

FLASH APP? It's only in EXTI2_IRQHandler().

But I didn't trigger the interrupt.

[LCE]

Disable the EXTI interrupt before the jump.

At least on a H7 a lot of de-inits and interrupt disabling is done before jumping.

Maybe before jumping you first de-init / change the GPIO config, and that triggers the EXTI interrupt.
So try to disable EXTI first, the de-init the GPIOs.

[LCE]

BTW, so many (and long) for-loops in an ISR are usually not considered good design, unless you have some very specific reason for that.

Why not just set a flag and then "print" in the main loop?

[fujiangmu]

It still stuck.

[fujiangmu]

If I set a flag,it is not timely enough in some condition.For example, more than 2 interrupts occur simultaneously.

 "print" in the main loop is DMA or other methods?

[LCE]

With "print" I mean any kind of UART output.

You could trigger a DMA UART TX in the ISR, then you don't have to wait there.

[LCE]

I'm not sure if I understand you correctly, right now it seems that the jump to the bootloader happens from within the ISR without any de-initialisations?

[TDK]

It sure looks like it did. The code in your interrupt is exactly what you show in your screenshot. I would recheck your assumptions here.