org.jivesoftware.openfire.nio.ConnectionHandler - ConnectionHandler reports IOException for session

org.jivesoftware.openfire.nio.ConnectionHandler - ConnectionHandler reports IOException for session: (SOCKET, R: /...:39657, L: /...:5222, S: 0.0.0.0/0.0.0.0:5222)
java.io.IOException: Connection reset by peer
at sun.nio.ch.FileDispatcherImpl.read0(Native Method)
at sun.nio.ch.SocketDispatcher.read(SocketDispatcher.java:39)
at sun.nio.ch.IOUtil.readIntoNativeBuffer(IOUtil.java:223)
at sun.nio.ch.IOUtil.read(IOUtil.java:197)
at sun.nio.ch.SocketChannelImpl.read(SocketChannelImpl.java:384)
at org.apache.mina.transport.socket.nio.SocketIoProcessor.read(SocketIoProcessor.java:218)
at org.apache.mina.transport.socket.nio.SocketIoProcessor.process(SocketIoProcessor.java:198)
at org.apache.mina.transport.socket.nio.SocketIoProcessor.access$400(SocketIoProcessor.java:45)
at org.apache.mina.transport.socket.nio.SocketIoProcessor$Worker.run(SocketIoProcessor.java:485)
at org.apache.mina.util.NamePreservingRunnable.run(NamePreservingRunnable.java:51)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
at java.lang.Thread.run(Thread.java:745)

What’s wrong with that? My server keeps reporting this, how to solve it? thank you