I ran into the issue when I am running the following code using the export.pkl model I had saved in my directory:
import fastai
from fastai.vision import *

def main():

    classes = ['Potato___Late_blight',
               'Cherry_(including_sour)___healthy',
               'Apple___Black_rot',
               'Apple___Apple_scab',
               'Cherry_(including_sour)___Powdery_mildew',
               'Potato___healthy',
               'Apple___Cedar_apple_rust',
               'Potato___Early_blight',
               'Apple___healthy']

    #load predictor
    predictor = load_learner('.')
    img = open_image('apple_black_rot1.jpg')
    pred,pred_idx,probs = predictor.predict(img)

    print(classes[pred_idx])

if __name__=="__main__":
    main()

The same error pops up along with various warnings. Is there any fix to this yet?