I got the following message after running my Flask project on another system.
The application ran all the time without problems:

Error: While importing 'app', an ImportError was raised:

Traceback (most recent call last):
  File "c:usersUserappdatalocalprogramspythonpython39libsite-packagesflaskcli.py", line 214, in locate_app
    __import__(module_name)
  File "C:UsersUserDesktopProjektapp__init__.py", line 3, in <module>
    from flask_restx import Namespace, Api
  File "c:usersUserappdatalocalprogramspythonpython39libsite-packagesflask_restx__init__.py", line 5, in <module>
  File "c:usersUserappdatalocalprogramspythonpython39libsite-packagesflask_restxapi.py", line 50, in <module>
    from .swagger import Swagger
  File "c:usersUserappdatalocalprogramspythonpython39libsite-packagesflask_restxswagger.py", line 18, in <module>
    from werkzeug.routing import parse_rule
ImportError: cannot import name 'parse_rule' from 'werkzeug.routing' (c:usersUserappdatalocalprogramspythonpython39libsite-packageswerkzeugrouting__i
nit__.py)

My requirements.txt

Flask~=2.1.2
psycopg2-binary==2.9.3
Flask-SQLAlchemy==2.5.1
flask-restx==0.5.1
qrcode~=7.3.1
django-qrcode~=0.3
PyPDF2==2.6.0
reportlab~=3.6.10
WTForms~=3.0.1
flask-bootstrap==3.3.7.1
flask-wtf==1.0.1