Total War rages in the Old World (opens in new tab), but some players are struggling to feel the heat of battle. Due to launch-day server load, "a few hundred" players are failing to connect, causing a crash. Never fear! Sega is on hand with a quick and dirty fix: set Steam to offline mode. I did say quick and dirty.
That ought to remedy 90% of crashes. I'm told the remainder are due to graphics drivers. Update your Nvidia (opens in new tab) or AMD drivers (opens in new tab) and perform Steam's most hallowed ritual—Verify Intergrity of Game Cache. Navigate to TW: Warhammer (opens in new tab)'s Properties > Local Files > Verify Intergrity of Game Cache.
Sega predicts the issues will dissipate as the day wears on, but in the meantime you can find extra support here (opens in new tab).