Start jupyter notebook and report error type object 'IOLoop' has no attribute 'initialized'

1. Problem description

        When installing and running jupyter notebook, an error message "type object 'IOLoop' has no attribute 'initialized' appears, as shown in the following figure:

Two, the solution

        The installed tornadoversion does not match jupyter, enter in the terminal:

conda install tornado=4.5

        After the installation is complete, you can use Jupyter notebook normally.