Starting atsserver: Unable to start LinuxGSM

[chandro]

Hello, i am installing LinuxGSM in a ubuntu 20 server brand new. all the other steps are OK but i still getting this error

atsserver@ats3-kc-xhandro-com:$ ./atsserver start
fetching GitHub [ command_start.sh ] ... OK
[ .... ] Starting atsserver: fetching GitHub [ check_root.sh ] ... OK
fetching GitHub [ check_system_dir.sh ] ... OK
fetching GitHub [ check_executable.sh ] ... OK
fetching GitHub [ check_logs.sh ] ... OK
[ INFO ] Starting atsserver: Checking for log files: Creating log files
creating log directory [ /home/atsserver/log ] ... SKIP
creating script log directory [ /home/atsserver/log/script ] ... SKIP
creating script log [ /home/atsserver/log/script/atsserver-script.log ] ... SKIP
creating console log directory [ /home/atsserver/log/console ] ... SKIP
creating console log [ /home/atsserver/log/console/atsserver-console.log ] ... SKIP
creating symlink to steam log directory [ /home/atsserver/log/steam -> /home/atsserver/.steam/steam/logs ] ... OK
fetching GitHub [ check_config.sh ] ... OK
fetching GitHub [ check_status.sh ] ... OK
fetching GitHub [ fix_steamcmd.sh ] ... OK
[ OK ] Starting atsserver: Applying steamclient.so sdk64 hardlink fix: American Truck Simulator
[ OK ] Starting atsserver: Applying steamclient.so sdk32 link fix: American Truck Simulator
fetching GitHub [ core_logs.sh ] ... OK
[ .... ] Starting atsserver: LinuxGSMno server running on /tmp/tmux-1000/atsserver-bba756e4
[ FAIL ] Starting atsserver: Unable to start LinuxGSM
atsserver@ats3-kc-xhandro-com:$

log shows this error:

Feb 09 07:12:06.047 atsserver: START: FAIL: Unable to start LinuxGSM
Feb 09 07:12:06.101 atsserver: START: INFO: LinuxGSM version: v25.1.1
Feb 09 07:12:06.115 atsserver: START: FAIL: core_exit.sh exiting with code: 1

how can i fix it?

thanks