[FIXED] ImportError: No module named 'flask.ext'

Issue

When I import a Flask extension like this, it works fine:

from flask_module import Module

So the extension is installed correctly.

But whenever I try to import a Flask extension like this:

from flask.ext.module import Module

I get the following error: ImportError: No module named 'flask.ext'

What is going wrong here?

I'm not sure if this information is useful but anyway:

1. I haven't found extensions that do work in the last way
2. I use Windows 10, Python3.5 and Flask 1.0.2
3. I'm in a virtual envirionment

Solution

The "flask.ext" style of naming/importing modules has been deprecated since 2016. Here's the reasoning. You should use the first style you described instead:

# Use this import format
from flask_sqlalchemy import SQLAlchemy

As for the suggestion that you install your flask packages globally, this somewhat defeats the purpose of using a venv in the first place. It makes it impossible to use pip freeze --local > requirements.txt to only save relevant packages, opening you up to package version conflicts.

Answered By - Nick K9