Hello, Is it possible to set a constant nullspace for a NonlinearVariationalSolver? I tried the following: order = 2 V3 = FunctionSpace(mesh, "CG", order) V1 = FunctionSpace(mesh, "BDM", order) V2 = FunctionSpace(mesh, "DG", order-1) W = MixedFunctionSpace([V3, V1, V2]) v_basis = VectorSpaceBasis(constant=True) null_space = MixedVectorSpaceBasis(W, [W.sub(0), W.sub(1), v_basis]) # Build Nonlinear Solver uprob = NonlinearVariationalProblem(L, w1) usolver = NonlinearVariationalSolver(uprob, nullspace=null_space, solver_parameters = { 'snes_max_it': '50', 'snes_rtol': '1e-12', 'mat_type': 'aij', 'ksp_type': 'preonly', 'pc_type': 'lu', 'snes_monitor': True, 'snes_view': False, 'snes_converged_reason': True, 'ksp_converged_reason': True}) but the linear solver did not converge: 0 SNES Function norm 7.964422825545e-02 Linear firedrake_1_ solve did not converge due to DIVERGED_PCSETUP_FAILED iterations 0 PCSETUP_FAILED due to FACTOR_NUMERIC_ZEROPIVOT Nonlinear firedrake_1_ solve did not converge due to DIVERGED_LINEAR_SOLVE iterations 0 I can send the full code if necessary. I'm trying to solve Navier-Stokes in velocity-vorticity-pressure formulation (https://arxiv.org/pdf/1604.00257.pdf) but the solver doesn't converge. If I add a small parameter times a pressure mass-matrix, the solver converges, but I was hoping to avoid doing this. Thanks, Sander