HAL_FLASH_Program problem on STM32C071CB

[eric239955_stm1_stmicro]

I'm using HAL_FLASH_Program(FLASH_TYPEPROGRAM_DOUBLEWORD, 32-bit-addr, 64-bit-data) and it crashes with an 0xfffffff7 exception.  Has anyone else seen this?  I've checked that the addresses are aligned to 64-bit boundary.

[Tesla DeLorean]

Crashes or Hard Faults? Where's this Exception# reported?

Is the memory Erased? You get one-shot to program it