[2019] Server Error: Backend rejected the challenge response

The Backend rejected the challenge response error is usually related to our anti-cheat service, Easy Anti-Cheat.

Try verifying integrity via Steam or if unsuccessful, repair the Easy Anti-Cheat client using the EasyAntiCheat_Setup executable located here:

C:\Program Files (x86)\Steam\steamapps\common\Warhammer Vermintide 2\installers\EasyAntiCheat