Not how I coded it, but it used to work on STM32F103RET6 parts.
Device_Serial0 = *((unsigned long *)0x1FFFF7E8); Device_Serial1 = *((unsigned long *)0x1FFFF7EC); Device_Serial2 = *((unsigned long *)0x1FFFF7F0); Suggest you park your JTAG debugger memory window in the region, and confirm you can see the boot loader.
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