We are getting frequent error log once we migrated from jboss 5 to wildfly 8.2

Exception Details
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2015-08-03 08:23:51,656 [ERROR] [default I/O-29] [request] [] [] UT005001: An exception occurred processing the request: java.lang.IllegalArgumentException: URLDecoder: Illegal hex characters in escape (%) pattern - For input string: "2S"
at java.net.URLDecoder.decode(URLDecoder.java:194)
at io.undertow.util.URLUtils$QueryStringParser.decode(URLUtils.java:228)
at io.undertow.util.URLUtils$QueryStringParser.parse(URLUtils.java:217)
at io.undertow.util.URLUtils.parseQueryString(URLUtils.java:52)
at io.undertow.server.protocol.ajp.AjpRequestParser.parse(AjpRequestParser.java:387)
at io.undertow.server.protocol.ajp.AjpReadListener.handleEvent(AjpReadListener.java:160)
at io.undertow.server.protocol.ajp.AjpReadListener.handleEvent(AjpReadListener.java:53)
at org.xnio.ChannelListeners.invokeChannelListener(ChannelListeners.java:92)
at org.xnio.conduits.ReadReadyHandler$ChannelListenerHandler.readReady(ReadReadyHandler.java:66)
at org.xnio.nio.NioSocketConduit.handleReady(NioSocketConduit.java:88)
at org.xnio.nio.WorkerThread.run(WorkerThread.java:539)