Yes @Mun_Chung_Wong
There is version issue with C3 assignment and you did the right way to resolve your issue.
Another way would be
Learners can reload the colab from the classroom or just add these lines at the top of their existing notebook (then run everything again to generate a new model file):
!pip install tf-keras==2.15 --quiet
!pip install tensorflow==2.15 --quiet
!pip install keras==2.15 --quiet
This would be required with course 3 as well as course 4 assignment but not all assignment.
Regards
DP