The BACKEND REJECTED THE CHALLENGE RESPONSE error OR being unable to connect to other players, craft or open Spoils of War indicates that you may be playing on the 'Modded' realm. If this is not applicable to you, it is issue with our anti-cheat service, Easy Anti-Cheat.
If the solutions listed below have not helped with your issue, please contact Easy Anti-Cheat directly: https://www.easy.ac/en-us/support/game/contact/tech/
Switch Realms
The most common cause of this error is when a player has the Modded realm selected, as opposed to the Official realm.
Your realm can be changed within the Vermintide 2 launcher, using the checkboxes on the right-hand side of the 'Play' button.
Remove the Easy Anti-Cheat Certificates & Install/Repair Easy Anti-Cheat
- Navigate to: C:\Program Files (x86)\Steam\steamapps\common\Warhammer Vermintide 2\EasyAntiCheat
- Delete the 'Certificates' directory
- Navigate to: C:\Program Files\Steam\steamapps\common\Warhammer Vermintide 2\installers\EasyAntiCheat
- Run the EasyAntiCheat_Setup installer and proceed as instructed
- Then use the 'Verify Integrity of Game Files' option as instructed below
Verify Integrity of Game Files
The 'Verify Integrity of Game Files' option is accessible via the Steam client and will ensure the installation is complete.
- Right-click Vermintide 2 in your Steam library sidebar
- Select 'Properties'
- Select the 'Local Files' tab
- Select the 'Verify Integrity of Game Files' button
- When complete, close and reopen Steam