Erase concept in flashing phase

[KKane]

Hello, when we flash binary file by using st link utility or cube programmer, previously flashed binary data are automatically erased ?

For example, flashing to head of sector 0. If previously flashed code size is bigger than new one, previously code stays partially ?

BR

[Uwe Bonnes]

For flashing new data into a page or a sector, the page or sector needs to be erased first. Most flashing programm will do that transparent. So, if you earlier program used more pages or sectors than the new programm you flash, the additional pages/sectors will keep the old content. Use mass erase to erase all the flash.