  The NOvA experiment is an off-axis long-baseline neutrino oscillation
experiment measuring $\nu_{\mu}$ disappearance and $\nu_{e}$ appearance in a
$\nu_{\mu}$ beam originating at Fermilab. Oscillations are observed in the far
detector relative to measurements made in the near detector, with a full
simulation of the beam line and detectors being used to perform extrapolation
between them. The neutrino simulation uses the GENIE event generator, which
contains implementations of numerous theoretical neutrino interaction models
applied to a variety of nuclear targets. However, recent data, recent
reanalysis of extant data, and continued development of theoretical models have
brought to light deficiencies in the default GENIE cross section model, which
informs the predicted spectra used to infer oscillation parameters. We explore
how uncertainties in this model, together with modifications to GENIE version
2.12.2 based on external information and NOvA Near Detector (ND) data, affect
NOvA's oscillation parameter inferences. We also discuss how these
uncertainties can be mitigated by judicious analysis design, including usage of
the ND data.
