I suspect you face this problem because you are using the older version 0.7 notebooks but you are installing fastai library version 1.0.
!pip install https://github.com/fastai/fastai/archive/master.zip
The line above will download and install fastai lib latest version (1.0 and above). If that’s not your intention, please install fastai lib version 0.7 (the version before 1.0).
Updates:
- See this thread. The solution is in there.