Hi all Because of a combination of settings, our code passes through this line: https://gitlab.com/petsc/petsc/-/blob/main/src/ksp/pc/impls/fieldsplit/field... i.e. the matrices associated with each of the sub-KSPs of a fieldsplit are destroyed and then re-created later. The thing is that one of these destroyed matrices had a near nullspace attached, which is lost because the new matrix does not have it anymore. Is this a bug or are we missing something? I'll need some time to come up with a MWE showing how the near nullspace is lost, but if its needed I can take a stab at it. -- jeremy [https://gitlab.com/uploads/-/system/project/avatar/13882401/PETSc_RBG-logo.png]<https://gitlab.com/petsc/petsc/-/blob/main/src/ksp/pc/impls/fieldsplit/fieldsplit.c?ref_type=heads#L692> src/ksp/pc/impls/fieldsplit/fieldsplit.c · main · PETSc / petsc · GitLab<https://gitlab.com/petsc/petsc/-/blob/main/src/ksp/pc/impls/fieldsplit/fieldsplit.c?ref_type=heads#L692> PETSc, pronounced PET-see (the S is silent), is a suite of data structures and routines for the scalable (parallel) solution of scientific applications modeled by partial differential equations. gitlab.com