With the latest petsc-dev I get the following error in many examples (e.g. src/ksp/ksp/examples/tutorials/ex12.c ): [0]PETSC ERROR: Object is in wrong state! [0]PETSC ERROR: Must call MatXXXSetPreallocation() or MatSetUp() on argument 1 "mat" before MatGetOwnershipRange()! I guess the idea is to add MatSetUp() in all examples? Or will this error be removed eventually? Jose