GPO - Minimum password length = 15 not applying

Hello,

I got trouble to activate the 15 characters minimum password length =15 to my Windows 2016 domain servers.

The Domain Controllers are on 2012 r2 OS.

Details :

Domain default GPO : set the password length to 14 character (for 2008 and 2012 domain servers) -> working fine.

GPO for 2k16 servers : I tried to set the settings by two different way :

-> manually update the GPTTMPL.inf file to set to 15 characters for the 2016 GPO

-> Launching GPMC.MSC on a Windows 2016 servers, and modify the value on the GPO to 15 characters.

Both ways, when i ran a gpupdate/force on my 2016 servers, it can't apply the settings to 15 characters :

Problem seems like the GPO_2k16 can't replace the default domain policy Password Minimum length to 15 character.

Error on Event Log : 0x57 : The parameter is incorrect. Troubleshooting 1202 events.

How to deal with such case ?

I need to have the 2008 and 2012 servers password minimum length to 14 characters, and 2016 to 15 characters.

Some more logs (winlogon.log) :

----Configure Security Policy...
        Start processing undo values for 7 settings.
        There is already an undo value for group policy setting <MinimumPasswordLength>.
        There is already an undo value for group policy setting <PasswordHistorySize>.
        There is already an undo value for group policy setting <MaximumPasswordAge>.
        There is already an undo value for group policy setting <MinimumPasswordAge>.
        There is already an undo value for group policy setting <PasswordComplexity>.
        There is already an undo value for group policy setting <RequireLogonToChangePassword>.
        There is already an undo value for group policy setting <ClearTextPassword>.
Error 87: The parameter is incorrect.
     Error configuring password information.
        Start processing undo values for 3 settings.
        There is already an undo value for group policy setting <LockoutBadCount>.
        There is already an undo value for group policy setting <ResetLockoutCount>.
        There is already an undo value for group policy setting <LockoutDuration>.
        There is already an undo value for group policy setting <ForceLogoffWhenHourExpire>.
    Configure account force logoff information.