Galaxy S9+ update Android Pie

[Siavash]

I bought S9+ four months ago and when I want update OS to android Pie, it says:
The latest update has already been installed.
and its security patch didn’t update since November 1, 2018.
Why didn’t I receive new android version? My current version is android 8.0.0

[BruceH]

Hi @Siavash,

Could you send me your IMEI-number through a private message so I can do an IMEI-check to see where your phone is from? 

[Siavash]

I know, it's from Iran.

[BruceH · Accepted solution]

Then you could try checking for updates with Smart Switch. If this doesn't work, I suggest that you visit a service center with your proof of purchase and your ID. They can manually flash the firmware for you.