I have Geoserver 2.2.4 installed - which allows GetFeatureInfo to be returned as json
If I make the following call
http://[servername]/geoserver/[namespace]/wms?LAYERS=[layername]&QUERY_LAYERS[layername]&STYLES=&SERVICE=WMS&VERSION=1.3&REQUEST=GetFeatureInfo&BBOX=299856.403448%2C528892.700948%2C300279.736552%2C529316.034052&FEATURE_COUNT=10&HEIGHT=600&WIDTH=600&FORMAT=image%2Fpng&INFO_FORMAT=application%2Fjson&SRS=EPSG%3A27700&X=249&Y=447&EXCEPTIONS=application%2Fjson
I get a exception response of
Invalid format 'application/json', supported formats are [text/plain, application/vnd.ogc.gml, application/vnd.ogc.gml/3.1.1, text/html]
I have checked getcapabilities for this service and only the following are available
<GetFeatureInfo>
<Format>text/plain</Format>
<Format>application/vnd.ogc.gml</Format>
<Format>application/vnd.ogc.gml/3.1.1</Format>
<Format>text/html</Format>
</GetFeatureInfo>
So is there any extra config I need to do to Geoserver to get it to output in json for GetFeatureInfo?