From Sony:
Benefits and improvements from the latest update:
*1: This function is only for A-mount lenses which can adapt to 8 or 10 fps (maximum) tracking AF-C shooting. See here for details.
*2: Raw data recorded by the ILCE-9 with firmware Ver. 1.00 or 1.01 could disappear. Please backup your raw data files, even if you’re updating the system software to Ver. 1.10.
Download: Sony a9 Firmware v.1.10