flash related issues of STM32F103 series

[liuxc]

When using the STM32F103 series, it is occasionally found that the content of some flash addresses will be automatically written as 0xFF when powering on.

and sometimes it's written as 0x00.

I want to know why does this happen? or under what circumstances does this phenomenon occur?

[STOne-32]

Dear @liuxc ,

Welcome in STM32 Community. This behavior should never happen with an STM32F1 MCU in normal operations , I would suggest to check if the device is genuine and made by STMicroelectronics.   
And You can also do a full flash Erase and program again the MCU to see if the behavior is the same ? 
Hope it helps you .

STOne-32