WFS GetFeature request (version 1.0.0) does not support "matchCase" option. It throws an exception. And geoserver therefore throws it.
Merged and backported to 14.x and 13.x (since it was a small change)
This pull implements the improvement:https://github.com/geotools/geotools/pull/1068
WFS GetFeature request (version 1.0.0) does not support "matchCase" option. It throws an exception. And geoserver therefore throws it.