Does anyone have any idea what the following error message is supposed to be telling me? It appears to be coming from an attempt to make a copy of MPI_COMM_SELF using MPI_Comm_dup. Abort(66703622) on node 4 (rank 4 in comm 0): Fatal error in internal_Intercomm_create: Invalid rank, error stack: internal_Intercomm_create(134): MPI_Intercomm_create(comm=0x84000005, 0, comm=0x84000003, 3, 0, newintercomm=0x7fffffffcd68) failed internal_Intercomm_create(102): Local and remote leaders must be different processes Bruce Palmer