Hi, I am having this error and I don't quite understand it:

java.io.InvalidClassException: [LdominogameServer.Tile;; serializable and externalizable flags conflict
at java.io.ObjectStreamClass.readNonProxy(ObjectStrea mClass.java:647)
at java.io.ObjectInputStream.readClassDescriptor(Obje ctInputStream.java:827)
at java.io.ObjectInputStream.readNonProxyDesc(ObjectI nputStream.java:1583)
at java.io.ObjectInputStream.readClassDesc(ObjectInpu tStream.java:1514)
at java.io.ObjectInputStream.readArray(ObjectInputStr eam.java:1642)
at java.io.ObjectInputStream.readObject0(ObjectInputS tream.java:1341)
at java.io.ObjectInputStream.readObject(ObjectInputSt ream.java:369)
at dominogameClient.GameGUI$constantReading.run(GameG UI.java:1222)
at java.lang.Thread.run(Thread.java:722)

I've been reading about it, but I still don't know where to start looking for it.
What is the reason for its cause?

If it helps, the code at line 1222 is: Object obj = Objectin.readObject();

from:
Java Code:
                while (true) {
                    Thread.sleep(1);
                    Object obj = Objectin.readObject();
                    filterData(obj);
                }
thnx