Change FortiGate inspection mode

Hi all,

I need your help because I would like to change the inspection mode to Proxy mode on multiple FortiGate already in production and managed by FortiManager that currently run in the Flow-based mode. These firewalls have a lot of policies applied.

I tried to make this change on 2 firewalls (one with multiple VDOM and another one without VDOM) but when I change the mode and try to re-install policies I have the message "ADOM package inspection mode is not consistent with its target VDOM inspection mode" in both cases.

What do I have to change to avoid this error message? 

Thanks for your help.

Regards