Hi to all, Well, I am already back and trying out the new ECJ version. This time I am able to run ECJ without any errors, but it seems there is still a problem with Uniform and Ephemeral Random Constants. In my runs, Uniform doesn't set up the ERCs values (they are always 0 during the run). I have checked Uniform.java, and I think the problem is that resetNode() is not called after protoClone(), as it happens in the other builders. I have changed this, and you can find my changed version attached to this email. After this change it seems to be working fine. <Uniform.java> I have now another problem, however: Before ECJ 13, I had implemented a Statistics class for serializing the best individuals in each generation. With ECJ 12, I was just using a standard ObjectOutputStream to serialize the individual to an external file, but this doesn't seem to work with ECJ 13 anymore - now Java complains that some classes are not serializable, and throws an exception. I have changed my class to use the new writeGenotype(..) method instead, but now I am getting this error message: FATAL ERROR: No node in the function set can be found that is equivalent to the node ERC[d4602857950892639882|0.5198876159976902|] when performing writeRootedTree(EvolutionState, GPType, GPFunctionSet, DataOutput). My ERC class is just a copy of ec.app.regression.func.RegERC. Is this a bug in ECJ or am I doing something wrong? Should I be using a different method for writing the individual to a file? Best regards, Artur Matos.