Hello, I am trying to integrate PETSc library to a serial program. The idea is that the serial program creates a linear equation system and then calls PETSc solver by MPI_Spawn and then solves this system in parallel. But when I execute MPI_Spawn the following error message occurs and the solver is not called. I couldn't find a solution to this error. Does anyone have an idea about it? Kind Regards, -- Nitel ********************************************************** Assertion failed in file socksm.c at line 590: hdr.pkt_type == MPIDI_NEM_TCP_SOCKSM_PKT_ID_INFO || hdr.pkt_type == MPIDI_NEM_TCP_SOCKSM_PKT_TMPVC_INFO internal ABORT - process 0 INTERNAL ERROR: Invalid error class (66) encountered while returning from MPI_Init. Please file a bug report. Fatal error in MPI_Init: Unknown error. Please file a bug report., error stack: (unknown)(): connection failure [cli_0]: aborting job: Fatal error in MPI_Init: Unknown error. Please file a bug report., error stack: (unknown)(): connection failure **********************************************************