[FIXED] (Connexion 3.0.2) ModuleNotFoundError: Please install connexion using the 'flask' extra

Issue

Problem

I use connextion with Flask. Today I upgraded connexion from 2.14.2 to 3.0.2 and see ModuleNotFoundError: Please install connexion using the 'flask' extra.

https://connexion.readthedocs.io/en/latest/quickstart.html

I checked the official documentation, which says "To leverage the FlaskApp, make sure you install connexion using the flask extra."

Question

How can I install connexion using the flask extra?
The documentation says the command is pip install connexion[<extra>], but I see an error message "no matches found: connexion[flask]".

% pip install connexion[flask]
zsh: no matches found: connexion[flask]

Environment

• Python 3.12.0
• Flask 3.0.0
• Connexion 3.0.2

Solution

https://github.com/spec-first/connexion/issues/779#issuecomment-441081238

I find this error was caused by zsh. pip install "connexion[flask]" worked.

Answered By - dmjy