ImportError: No module named 'pandas.core.internals.managers'; 'pandas.core.internals' is not a package
I had the same problem, but for me, it seemed to come from the pickle package / interaction with the pandas package. 
I had Pandas version 0.23.4.
I saved some pickle files with pandas.Dataframe.to_pickle, with python 3.6.6 & Pandas version 0.23.4.
Then I upgraded to python 3.7.2 (Pandas version 0.23.4), and was enabled to read thoses pickle files with pandas.Dataframe.read_pickle.
Next, I upgraded pandas to pandas 0.24.1, and it worked for me. I can read those files again.
When I tried to read a pickle file that saved by a former version of pandas, it yielded an ImportError.

ImportError: No module named 'pandas.core.internals.managers';
  'pandas.core.internals' is not a package

There was no hit on stackoverflow so i would like to share my solution for this particular problem.