Multiplayer instant out of sync

[Doggiva]

Me and my friend are trying after some months play multiplayer again and he doesn´t have all the same dlc as me.
When I launch the game and start, give it 10 seconds and it says out of sync. Never had a problem like this when we cant even start the game. Give me some options to try out,thanks.

 

[AndrewT]

Here are my standard things to look at in MP for this game:

- make sure all players have opened the required Steam ports in all their active firewalls (each player may have up to 3)
https://support.steampowered.com/kb_article.php?ref=8571-GLVN-8711
- all players delete their documents/paradox/ck2/gfx/ folders, and let the game recreate them
- use no mods at all
- all players use the same language in-game
- when anyone gets an OOS error, re-host the game immediately, as it will almost certainly crash soon
- start your multiplayer games and wait half a minute or so before unpausing without any player performing any action at all. Only after the game has been unpaused should players begin doing actions like setting up council, declaring war etc.

Good luck!