06_multicat - append error

Part 1 (2019)
#1

Hi everyone.

I was doing 06_multicat notebook and run into strange error (in the Regression part on the notebook):
AttributeError: 'NoneType' object has no attribute 'append' ,
after I try to learn.lr_find().

learn.fine_tune(3, 1e-2) also doesn’t work and throws the same error.

I have done previous notebooks and it was all fine. I didn’t change the code you have provided in this part. The forums don’t seem to have the answer for this.

I’m no expert, but it looks like there is a problem with cbs, whatever it is, and I found that it is a parameter in cnn_learner and it defaults to None. So, not sure how to go about it.

Any help is much appreciated.

Screenshot 2020-12-22 192747
Screenshot 2020-12-22 192747857×891 38.7 KB

#2

Many apologies! We have a fix now and will release it very soon today.

1 Like
#3

Hi, I still have the same problem with fastai 2.2.5. The error is thrown when executing learn.lr_find() or learn.fine_tune(3, 1e-2)

---------------------------------------------------------------------------
AttributeError                            Traceback (most recent call last)
<ipython-input-259-d81c6bd29d71> in <module>
----> 1 learn.lr_find()

...

/opt/conda/lib/python3.7/site-packages/fastai/learner.py in add_cb(self, cb)
    107         return self
    108 
--> 109     def remove_cbs(self, cbs):
    110         L(cbs).map(self.remove_cb)
    111         return self

AttributeError: 'NoneType' object has no attribute 'append'

It’s quite strange that the end of the stack trace shows no call to append, but my Python knowledge is limited.

Any help is appreciated.

#4

Sorry, false alarm. The problem disappeared after I restarted the VM.