On some Linux machines running Ubuntu 22 and above, Intel MPI may have issues running across more than one machine. If your Forte run hangs or fails with the following message:

mpiexec@machinename] check_exit_codes (../../../../../src/pm/i_hydra/libhydra/demux/hydra_demux_poll.c:117): unable to run bstrap_proxy on machinename(pid <number>, exit code 768)
[mpiexec@machinename] poll_for_event (../../../../../src/pm/i_hydra/libhydra/demux/hydra_demux_poll.c:159): check exit codes error
[mpiexec@machinename] HYD_dmx_poll_wait_for_proxy_event (../../../../../src/pm/i_hydra/libhydra/demux/hydra_demux_poll.c:212): poll for event error
[mpiexec@machinename] HYD_bstrap_setup (../../../../../src/pm/i_hydra/libhydra/bstrap/src/intel/i_hydra_bstrap.c:1061): error waiting for event
[mpiexec@machinename] HYD_print_bstrap_setup_error_message (../../../../../src/pm/i_hydra/mpiexec/intel/i_mpiexec.c:1027): error setting up the bootstrap proxies
[mpiexec@machinename] Possible reasons:
[mpiexec@machinename] 1. Host is unavailable. Please check that all hosts are available.
[mpiexec@machinename] 2. Cannot launch hydra_bstrap_proxy or it crashed on one of the hosts. Make sure hydra_bstrap_proxy is available on all hosts and it has right permissions.
[mpiexec@machinename] 3. Firewall refused connection. Check that enough ports are allowed in the firewall and specify them with the I_MPI_PORT_RANGE variable.
[mpiexec@machinename] 4. Ssh bootstrap cannot launch processes on remote host. Make sure that passwordless ssh connection is established across compute hosts.
[mpiexec@machinename]    You may try using -bootstrap option to select alternative launcher.

then add:

export I_MPI_HYDRA_IFACE="eth0"

setting this variable in either the Forte User Interface Linux Settings Panel or in your job submission script or environment and try your run again. This is an issue known to Intel.