The looks to be an error from a fairly old version of MPICH. Have you tried installing the latest version (4.1.2) available on our website or Github? Ken From: Nazmul Haque via discuss <[email protected]> Reply-To: "[email protected]" <[email protected]> Date: Sunday, June 25, 2023 at 11:38 PM To: "[email protected]" <[email protected]> Cc: Nazmul Haque <[email protected]> Subject: [mpich-discuss] MPI_Init fail Hello, I have installed mpich2 and tried to run an executable with 'mpiexec -n 8 lmp -in .....' but it shows error, replying that mpi_init is unable to connect to the local host. How can I solve this? I have also attached the image of the error. Thank you for your time. Regards, Nazmul