Arma 3 Headless Client Steam Authentication Failed Jun 2026

start arma3.exe -client -appid=107410 -connect=127.0.0.1 -port=2302 -password=pass -nosound -name=HC

If Solution 1 fails, you must explicitly tell the HC which Steam AppID to use. Add this to your HC command line: arma 3 headless client steam authentication failed

Add the local IP of the HC to the headlessClients[] and localClient[] arrays: start arma3

If you are absolutely stuck and running a private LAN server, you can disable Steam authentication entirely by adding -nosteam to both the server and HC launch parameters. This prevents any player from connecting except local HCs. arma 3 headless client steam authentication failed