: Ensure the Headless Client is loading the exact same mod list as the server. If mod names have spaces, use double quotes around the -mod argument in your startup .bat file (e.g., "-mod=@Mod Name;@Other Mod" ) to prevent loading failures.
If your main server runs BattleEye (it should), the HC must authenticate through it. Add this:
arma3server.exe -client -connect=127.0.0.1 -port=2302 -password=ServerPass -mod=@modlist Quotes for Mods : If your mod list contains spaces, wrap the entire arma 3 headless client steam authentication failed hot
Navigate to your BattlEye folder on the server. Open BEServer_x64.cfg (or .cfg for your port). Add:
Validate content ownership
The "Steam Authentication Failed" error is almost never a CD-key issue. It is a .
Add this to your HC launch line:
Why Steam authentication matters for the Headless Client