  A NuSTAR/Swift observation of the luminous Seyfert 1 galaxy 1H 0419-577 taken
during 2015 reveals one of the most extreme high energy cut-offs observed to
date from an AGN - an origin due to thermal Comptonization would imply a
remarkably low coronal temperature $kT \sim 15$ keV. The low energy peak of the
spectrum in the hard X-ray NuSTAR band, which peaks before the expected onset
of a Compton hump, rules out strong reflection as the origin of the hard excess
in this AGN. We show the origin of the high energy rollover is likely due to a
combination of both thermal Comptonization and an intrinsically steeper
continuum, which is modified by absorption at lower energies. Furthermore,
modeling the broadband XUV continuum shape as a colour-corrected accretion
disc, requires the presence of a variable warm absorber to explain all flux and
spectral states of the source, consistent with the previous work on this AGN.
While absorber variations produce marked spectral variability in this AGN,
consideration of all flux states allows us to isolate a colourless component of
variability that may arise from changes in the inner accretion flow, typically
at around $10 \, r_g$.
