Hi, I'm trying to run Titan2D on a linux. I found a similar problem on a different system. ( Ubuntu PC / CentOS Cluster ) Small operations, the error does not occur. However, In the case of long simulation error occur. The error message is shown below. Fatal error in PMPI_Isend: Internal MPI error!, error stack: PMPI_Isend(148): MPI_Isend(buf=0x244c53c0, count=45, dtype=USER<struct>, dest=13, tag=22676, MPI_COMM_WORLD, request=0x227ab074) failed (unknown)(): Internal MPI error! Fatal error in PMPI_Test: Other MPI error, error stack: PMPI_Test(168)............: MPI_Test(request=0x147a6068, flag=0x7fff9bd5098c, status=0x7fff9bd50960) failed MPIR_Test_impl(63)........: dequeue_and_set_error(596): Communication error with rank 2 Fatal error in PMPI_Test: Other MPI error, error stack: PMPI_Test(168)............: MPI_Test(request=0x2deaf058, flag=0x7fff88bd375c, status=0x7fff88bd3730) failed MPIR_Test_impl(63)........: dequeue_and_set_error(596): Communication error with rank 2 Fatal error in PMPI_Barrier: Other MPI error, error stack: PMPI_Barrier(425)...........: MPI_Barrier(MPI_COMM_WORLD) failed MPIR_Barrier_impl(292)......: MPIR_Barrier_or_coll_fn(121): MPIR_Barrier_intra(83)......: dequeue_and_set_error(596)..: Communication error with rank 10 Fatal error in PMPI_Barrier: Other MPI error, error stack: PMPI_Barrier(425)...........: MPI_Barrier(MPI_COMM_WORLD) failed MPIR_Barrier_impl(306)......: MPIR_Bcast_impl(1321).......: MPIR_Bcast_intra(1155)......: MPIR_Bcast_binomial(213)....: Failure during collective MPIR_Barrier_impl(292)......: MPIR_Barrier_or_coll_fn(121): MPIR_Barrier_intra(83)......: dequeue_and_set_error(596)..: Communication error with rank 0 Fatal error in PMPI_Isend: Other MPI error, error stack: PMPI_Isend(148)..........: MPI_Isend(buf=0x282dbdc0, count=260, dtype=USER<struct>, dest=10, tag=22683, MPI_COMM_WORLD, request=0x26b3a9b8) failed MPID_nem_lmt_RndvSend(81): MPIDI_CH3_RndvSend(63)...: failure occurred while attempting to send RTS packet MPIDI_CH3_iStartMsg(36)..: Communication error with rank 10 Fatal error in PMPI_Test: Other MPI error, error stack: PMPI_Test(168)..................: MPI_Test(request=0xa66b46c, flag=0x7fff849b92dc, status=0x7fff849b92b0) failed MPIR_Test_impl(63)..............: MPIDI_CH3U_Recvq_FDU_or_AEP(380): Communication error with rank 3 Thanks, Park Bokuk