NameError: name 'CallbackHandler' is not defined

Part 1 (2020)
1

I am getting an error in GCP notebook after running the following code

#id first_training
#caption Results from the first training
# CLICK ME
from fastai.vision.all import *
path = untar_data(URLs.PETS)/'images'

def is_cat(x): return x[0].isupper()
dls = ImageDataLoaders.from_name_func(
    path, get_image_files(path), valid_pct=0.2, seed=42,
    label_func=is_cat, item_tfms=Resize(224))

learn = cnn_learner(dls, resnet34, metrics=error_rate)
learn.fine_tune(1)

error
error982×627 116 KB

I have followed all the instructions on GCP setup page, this has not been resolved in other threads as well.

fastai.version
'1.0.61

fastcore.version
‘1.3.20’