Hi Pierre, I would say the answer to that question is "no, its not expected". We will look into fixing it. It seems like the default tolerances are being set to zero and the result is an inability to satisfy the constraints or gradient of the Lagrangian to that small of a tolerance. Thanks for point this out to us! We will get it resolved. Thanks, Todd. On 8/4/20, 12:12 PM, "petsc-dev on behalf of Pierre Jolivet" <[email protected] on behalf of [email protected]> wrote: Hello, If I comment line 89 and 90 of src/tao/constrained/tutorials/ex1.c from master, the example deadlocks with a single process. Is this expected? Thanks, Pierre $ ./ex1 -tao_monitor ---- Constrained Problem ----- Solution should be f(1,1)=-2 0 TAO, Function value: 8., Residual: 8.48528 1 TAO, Function value: 1.28532, Residual: 10.7411 2 TAO, Function value: -2.56703, Residual: 1.87847 3 TAO, Function value: -2.03161, Residual: 0.12881 4 TAO, Function value: -1.99961, Residual: 0.0450855 5 TAO, Function value: -1.99993, Residual: 0.000916939 6 TAO, Function value: -1.99999, Residual: 6.69184e-05 7 TAO, Function value: -2., Residual: 7.15427e-06 8 TAO, Function value: -2., Residual: 7.15779e-07 9 TAO, Function value: -2., Residual: 7.15777e-08 10 TAO, Function value: -2., Residual: 7.15777e-09 11 TAO, Function value: -2., Residual: 7.15779e-10 12 TAO, Function value: -2., Residual: 7.15775e-11 13 TAO, Function value: -2., Residual: 7.1599e-12 14 TAO, Function value: -2., Residual: 7.1599e-13 15 TAO, Function value: -2., Residual: 7.22085e-14 16 TAO, Function value: -2., Residual: 6.44626e-15 17 TAO, Function value: -2., Residual: 1.00751e-15 18 TAO, Function value: -2., Residual: 1.70295e-17 19 TAO, Function value: -2., Residual: 1.70295e-18 20 TAO, Function value: -2., Residual: 1.70295e-19 21 TAO, Function value: -2., Residual: 1.70295e-20 22 TAO, Function value: -2., Residual: 1.70295e-21 23 TAO, Function value: -2., Residual: 1.70295e-22 24 TAO, Function value: -2., Residual: 1.70295e-23 25 TAO, Function value: -2., Residual: 1.70295e-24 26 TAO, Function value: -2., Residual: 1.70295e-25 27 TAO, Function value: -2., Residual: 1.70295e-26 28 TAO, Function value: -2., Residual: 1.70295e-27 29 TAO, Function value: -2., Residual: 1.70295e-28 30 TAO, Function value: -2., Residual: 1.70295e-29 31 TAO, Function value: -2., Residual: 1.70295e-30 32 TAO, Function value: -2., Residual: 1.70295e-31 33 TAO, Function value: -2., Residual: 1.70295e-32 34 TAO, Function value: -2., Residual: 1.70295e-33 35 TAO, Function value: -2., Residual: 1.70295e-34 36 TAO, Function value: -2., Residual: 1.70295e-35 37 TAO, Function value: -2., Residual: 1.70295e-36 38 TAO, Function value: -2., Residual: 1.70295e-37 39 TAO, Function value: -2., Residual: 1.70295e-38 40 TAO, Function value: -2., Residual: 1.70295e-39 41 TAO, Function value: -2., Residual: 1.70295e-40 42 TAO, Function value: -2., Residual: 1.70295e-41 43 TAO, Function value: -2., Residual: 1.70295e-42 44 TAO, Function value: -2., Residual: 1.70295e-43 45 TAO, Function value: -2., Residual: 1.70295e-44 46 TAO, Function value: -2., Residual: 1.70295e-45 47 TAO, Function value: -2., Residual: 1.70295e-46 48 TAO, Function value: -2., Residual: 1.70295e-47 49 TAO, Function value: -2., Residual: 1.70295e-48 50 TAO, Function value: -2., Residual: 1.70295e-49 51 TAO, Function value: -2., Residual: 1.70295e-50 52 TAO, Function value: -2., Residual: 1.70295e-51 ^C