As of Tuesday, December 24 9:00 UTC, a patch was released to fix a compatibility issue in preparation for the update from MONSTER HUNTER: WORLD to MONSTER HUNTER WORLD: ICEBORNE.
With this patch, the latest version of MONSTER HUNTER: WORLD is revision number 168031.
We apologize for any inconvenience this may have caused.
Important:
The latest version of MONSTER HUNTER: WORLD is revision number 168031.
You can verify the version number in the top-left corner when you launch the game
in windowed mode.
Keep in mind that you can only match with other players who have the same update
version as you.
For other questions, please visit the official MONSTER HUNTER: WORLD support portal below.
http://www.capcom.com/mhwsupport/