OMP_NUM_THREADS environment is not set.............Unknown command: communicate multi vel yes

Dear Users,
I am a new user of LAMMPS. I am trying to run a given file known as “UNIAXIAL COMPRESSION TEST IN SOILS” But it is not running as it is showing a warning and an error
Warning :OMP_NUM_THREADS environment is not set.
Error :Unknown command: communicate multi vel yes
Regards

Dear Users,
I am a new user of LAMMPS. I am trying to run a given file known as
"UNIAXIAL COMPRESSION TEST IN SOILS" But it is not running as it is showing
a warning and an error
Warning :OMP_NUM_THREADS environment is not set.

​this is just a warning.​

Error :Unknown command: communicate multi vel yes

​that means that the script you are trying to run was written for an old
version of LAMMPS. the communicate command has been removed and you need to
use comm_modify instead. please check out the manual for details on how to
use that command.

axel.​