demo-flask ImportError: cannot import name 'Markup' from 'jinja2'

[fredcy]

When I attempt to run the Flask demo it fails immediately:

ImportError: cannot import name 'Markup' from 'jinja2' (/home/example/test-saml/python3-saml/demo-flask/env/lib/python3.10/site-packages/jinja2/init.py)

I'm using Python 3.10.15 and the master branch of python3-saml. I have not touched any of the files like settings.json yet as I want to get a baseline first. Here are my steps:

cd demo-flask
python3 -m venv env
. env/bin/activate
pip install -r requirements.txt
python index.py

The ImportError happens immediately.

pip freeze shows that I'm getting these packages:

click==8.1.7
Flask==1.0
itsdangerous==2.2.0
Jinja2==3.1.4
MarkupSafe==3.0.2
Werkzeug==3.1.3

[fredcy]

If I install Flask and python3-saml per the following updated requirements.txt contents, then python index.py runs without crashing:

flask==3.1.0
python3-saml==1.16.0