Dear Tomasz, Please note, you get much better responses (faster) if you send mail to the firedrake list, rather than me individually.

On 6 May 2016, at 16:19, Tomasz Salwa [RPG] <mmtjs@leeds.ac.uk> wrote: [0] DMPlexCreateGmsh() line 247 in /tmp/pip-5Zhs5M-build/src/dm/impls/plex/plexgmsh.c [0] Invalid argument [0] Could not determine Plex facet for element 2241

Yet, if I comment the next to last line in the .geo file, then it runs.

I have no understanding of the intricacies of the Gmsh file format, or indeed what it does. However, your geo file appears not to be using the Transfinite Volume command correctly.