Dear all, What does this message mean: petsc4py.PETSc.Error: error code 77 [147] SNESSolve() line 4060 in /home2/y07/y07/fdrake/petsc/src/snes/interface/snes.c [147] SNESSolve_KSPONLY() line 40 in /home2/y07/y07/fdrake/petsc/src/snes/impls/ksponly/ksponly.c [147] KSPSolve() line 659 in /home2/y07/y07/fdrake/petsc/src/ksp/ksp/interface/itfunc.c [147] KSPSolve_GMRES() line 239 in /home2/y07/y07/fdrake/petsc/src/ksp/ksp/impls/gmres/gmres.c [147] KSPInitialResidual() line 69 in /home2/y07/y07/fdrake/petsc/src/ksp/ksp/interface/itres.c [147] KSP_PCApply() line 245 in /home2/y07/y07/fdrake/petsc/include/petsc/private/kspimpl.h [147] PCApply() line 482 in /home2/y07/y07/fdrake/petsc/src/ksp/pc/interface/precon.c [147] PCApply_FieldSplit_Schur() line 921 in /home2/y07/y07/fdrake/petsc/src/ksp/pc/impls/fieldsplit/fieldsplit.c [147] KSPSolve() line 602 in /home2/y07/y07/fdrake/petsc/src/ksp/ksp/interface/itfunc.c [147] KSPSetUp() line 393 in /home2/y07/y07/fdrake/petsc/src/ksp/ksp/interface/itfunc.c [147] PCSetUp() line 968 in /home2/y07/y07/fdrake/petsc/src/ksp/pc/interface/precon.c [147] PCSetUp_GAMG() line 526 in /home2/y07/y07/fdrake/petsc/src/ksp/pc/impls/gamg/gamg.c [147] PCGAMGCoarsen_AGG() line 1001 in /home2/y07/y07/fdrake/petsc/src/ksp/pc/impls/gamg/agg.c [147] smoothAggs() line 333 in /home2/y07/y07/fdrake/petsc/src/ksp/pc/impls/gamg/agg.c [147] Petsc has generated inconsistent data [147] !(matA_1 && !matA_1->compressedrow.use) I received it when trying to restart a parallel job from a checkpoint on Archer. cheers --cjc -- http://www.imperial.ac.uk/people/colin.cotter www.cambridge.org/9781107663916