Model persistence in Scikit-Learn?

Question

I am trying to save and load scikit-learn model but facing issues when the save and load are happening on different python versions. Here what I have tried:

1. Using pickle to save a model in python3 and deserialize in python2.This works for some of the models like LR,SVM but it fails for KNN.

   >>> pickle.load(open("inPy3.pkl", 'rb')) #KNN model
   ValueError: non-string names in Numpy dtype unpickling
   

2. Also , I tried to serialize and deserialize in json using jsonpickle but getting the following error.

   data = jsonpickle.encode(lr) #lr = logisticRegression Model
   jsonpickle.decode(data)
   AttributeError: 'dict' object has no attribute '__name__'
   

Also, I want to know if there is some utility which I can use to serialize and deserialize scikit-learn model objects to human readable format (json,xml,protobuf etc).