Hi team, The attached script is a trimmed down version of the sort of problem I'm trying to run. Running it on most machines (I've tried 4 machines), I got this output: $ python mytest.py 0 SNES Function norm 0.873814 1 SNES Function norm 0.245545 2 SNES Function norm 0.0178611 3 SNES Function norm 0.000156473 4 SNES Function norm 1.26023e-09 However, on my workstation in college (where I do most work unfortunately), I got: 0 SNES Function norm 0.873814 1 SNES Function norm 0.432782 2 SNES Function norm 0.0478636 3 SNES Function norm 0.0405004 4 SNES Function norm 0.0405004 5 SNES Function norm 0.0405004 6 SNES Function norm 0.0405004 7 SNES Function norm 0.0405004 8 SNES Function norm 0.0405004 9 SNES Function norm 0.0405004 10 SNES Function norm 0.0405004 I have tried to update and also reinstall firedrake, and pip list shows same version for FIAT, petsc, petsc4py, UFL (firedrake version is shown as 'unknown' though). The snes objects are identical as well. Is there anything else that I can check to see where the discrepancy occurs? Many thanks, -TJ