(I tried answering on your other thread but you deleted it, so posting here):
You should install it based on the following:
!pip install torchtext==0.8.1
!pip install -U fastbook
This way the proper torch versions etc will be installed. fastai does not officially support torch 1.8 yet, so you’ll still throw an error of:
ERROR: torchvision 0.9.0+cu101 has requirement torch==1.8.0, but you'll have torch 1.7.1 which is incompatible.
But the right packages will be installed later
The issue is torch breaking fastai’s requirements based upon what comes preinstalled in colab