from to 9.00 through standard software menus or USB updates is not possible . Sony's security measures are designed to prevent the system from accepting any firmware with a version number lower than the one currently installed.
Directly downgrading a Go to product viewer dialog for this item. ps4 downgrade 1302 to 900 top
: If you updated directly from 9.00 to 13.02, you could revert back to 9.00. If you updated from 13.01 to 13.02, you can only revert to 13.01. Hardware Requirements for Downgrading from to 9
However, a hardware-based "reversion" technique exists that allows users to switch back to the previously installed on that specific console. The Reversion Method: How It Works ps4 downgrade 1302 to 900 top