  With the high-resolution data from the Interface Region Imaging Spectrograph,
we detect a light wall above a sunspot light bridge in the NOAA active region
(AR) 12403. In the 1330 A slit-jaw images, the light wall is brighter than the
ambient areas while the wall top and base are much brighter than the wall body,
and it keeps oscillating above the light bridge. A C8.0 flare caused by a
filament activation occurred in this AR with the peak at 02:52 UT on 2015
August 28, and the flare's one ribbon overlapped the light bridge which was the
observational base of the light wall. Consequently, the oscillation of the
light wall was evidently disturbed. The mean projective oscillation amplitude
of the light wall increased from 0.5 Mm to 1.6 Mm before the flare, and
decreased to 0.6 Mm after the flare. We suggest that the light wall shares a
group of magnetic field lines with the flare loops, which undergo a magnetic
reconnection process, and they constitute a coupled system. When the magnetic
field lines are pushed upwards at the pre-flare stage, the light wall turns to
the vertical direction, resulting in the increase of the light wall's
projective oscillation amplitude. After the magnetic reconnection takes place,
a group of new field lines with smaller scales are formed underneath the
reconnection site and the light wall inclines. Thus, the projective amplitude
decreases remarkably at the post-flare stage.
