Alp I have found this problem, reproducible with release (see below using src/tao/unconstrained/tutorials/minsurf1) I was trying MFFD hessian with bntr. Using assembled hessian is fine (tf-oneapi) [szampini@localhost tutorials]$ ./minsurf1 -tao_smonitor -tao_type bntr -mx 10 -my 8 -tao_bnk_max_cg_its 3 -tao_gatol 1.e-4 ---- Minimum Surface Area Problem ----- mx: 10 my: 8 iter = 0, Function value 1.45591, Residual: 0.21372 iter = 0, Function value 1.43469, Residual: 0.205909 iter = 0, Function value 1.43469, Residual: 0.205909 iter = 1, Function value 1.42058, Residual: 0.0881207 iter = 2, Function value 1.41987, Residual: 0.10019 iter = 3, Function value 1.41797, Residual: 0.0209656 iter = 1, Function value 1.41775, Residual: 0.000288154 iter = 0, Function value 1.41775, Residual: 0.000288154 iter = 1, Function value 1.41775, Residual: 0.000207788 iter = 2, Function value 1.41775, Residual: 0.000123638 iter = 3, Function value 1.41775, Residual: 0.000117563 iter = 2, Function value 1.41775, Residual: < 1.0e-6 Using MFFD hessian error (using bnls segefaults, we should try to check all possible Tao solvers affected by this bug?) (tf-oneapi) [szampini@localhost tutorials]$ ./minsurf1 -tao_smonitor -tao_type bntr -mx 10 -my 8 -tao_bnk_max_cg_its 3 -tao_gatol 1.e-4 -tao_mf_hessian ---- Minimum Surface Area Problem ----- mx: 10 my: 8 iter = 0, Function value 1.45591, Residual: 0.21372 iter = 0, Function value 1.43469, Residual: 0.205909 iter = 0, Function value 1.43469, Residual: 0.205909 iter = 1, Function value 1.42058, Residual: 0.0881207 iter = 2, Function value 1.41987, Residual: 0.10019 iter = 3, Function value 1.41797, Residual: 0.0209656 [0]PETSC ERROR: --------------------- Error Message -------------------------------------------------------------- [0]PETSC ERROR: Object is in wrong state [0]PETSC ERROR: MatMFFDSetBase() has not been called, this is often caused by forgetting to call MatAssemblyBegin/End on the first Mat in the SNES compute function [0]PETSC ERROR: See https://petsc.org/release/faq/ for trouble shooting. [0]PETSC ERROR: Petsc Release Version 3.16.0, unknown [0]PETSC ERROR: ./minsurf1 on a arch-conda-tf-oneapi-single-real named localhost.localdomain by szampini Thu Oct 14 18:11:23 2021 [0]PETSC ERROR: Configure options --with-blaslapack-dir=/home/szampini/Devel/miniforge/envs/tf-oneapi --download-thrust --LDFLAGS=-liomp5 --with-debugging=0 --with-openmp --with-precision=single --with-fc=0 --download-h2opus --download-slepc --download-slepc-commit=origin/release PETSC_ARCH=arch-conda-tf-oneapi-single-real PETSC_DIR=/home/szampini/Devel/miniforge/Devel/petsc [0]PETSC ERROR: #1 MatMult_MFFD() at /home/szampini/Devel/miniforge/Devel/petsc/src/mat/impls/mffd/mffd.c:333 [0]PETSC ERROR: #2 MatMult_Shell() at /home/szampini/Devel/miniforge/Devel/petsc/src/mat/impls/shell/shell.c:1066 [0]PETSC ERROR: #3 MatMult() at /home/szampini/Devel/miniforge/Devel/petsc/src/mat/interface/matrix.c:2439 [0]PETSC ERROR: #4 KSP_MatMult() at /home/szampini/Devel/miniforge/Devel/petsc/include/petsc/private/kspimpl.h:346 [0]PETSC ERROR: #5 KSPCGSolve_STCG() at /home/szampini/Devel/miniforge/Devel/petsc/src/ksp/ksp/impls/cg/stcg/stcg.c:183 [0]PETSC ERROR: #6 KSPSolve_Private() at /home/szampini/Devel/miniforge/Devel/petsc/src/ksp/ksp/interface/itfunc.c:914 [0]PETSC ERROR: #7 KSPSolve() at /home/szampini/Devel/miniforge/Devel/petsc/src/ksp/ksp/interface/itfunc.c:1086 [0]PETSC ERROR: #8 TaoBNKComputeStep() at /home/szampini/Devel/miniforge/Devel/petsc/src/tao/bound/impls/bnk/bnk.c:477 [0]PETSC ERROR: #9 TaoSolve_BNTR() at /home/szampini/Devel/miniforge/Devel/petsc/src/tao/bound/impls/bnk/bntr.c:139 [0]PETSC ERROR: #10 TaoSolve() at /home/szampini/Devel/miniforge/Devel/petsc/src/tao/interface/taosolver.c:227 [0]PETSC ERROR: #11 main() at minsurf1.c:110 [0]PETSC ERROR: PETSc Option Table entries: [0]PETSC ERROR: -check_pointer_intensity 0 [0]PETSC ERROR: -mx 10 [0]PETSC ERROR: -my 8 [0]PETSC ERROR: -tao_bnk_max_cg_its 3 [0]PETSC ERROR: -tao_gatol 1.e-4 [0]PETSC ERROR: -tao_mf_hessian [0]PETSC ERROR: -tao_smonitor [0]PETSC ERROR: -tao_type bntr [0]PETSC ERROR: ----------------End of Error Message -------send entire error message to [email protected] Abort(73) on node 0 (rank 0 in comm 0): application called MPI_Abort(MPI_COMM_WORLD, 73) - process 0 Using fd is fine (tf-oneapi) [szampini@localhost tutorials]$ ./minsurf1 -tao_smonitor -tao_type bntr -mx 10 -my 8 -tao_bnk_max_cg_its 3 -tao_gatol 1.e-4 -tao_fd_hessian ---- Minimum Surface Area Problem ----- mx: 10 my: 8 iter = 0, Function value 1.45591, Residual: 0.21372 iter = 0, Function value 1.43469, Residual: 0.205909 iter = 0, Function value 1.43469, Residual: 0.205909 iter = 1, Function value 1.42058, Residual: 0.0881207 iter = 2, Function value 1.41987, Residual: 0.10019 iter = 3, Function value 1.41797, Residual: 0.0209656 iter = 1, Function value 1.41775, Residual: 0.000342734 iter = 0, Function value 1.41775, Residual: 0.000342734 iter = 1, Function value 1.41775, Residual: 0.000275372 iter = 2, Function value 1.41775, Residual: 0.000148513 iter = 3, Function value 1.41775, Residual: 0.000150663 iter = 2, Function value 1.41775, Residual: < 1.0e-6 -- Stefano