I’m working through: http://flask.pocoo.org/docs/1.0/tutorial/

I’ve written __init__.py (code here: http://codepad.org/4FGIE901) in a /flaskr/ directory, set up a virtual environment called ‘venv’ and installed Flask.

I then ran these commands — on the command line, in the flaskr directory – as ‘Run the application’ advises: (export FLASK_APP=flaskr, export FLASK_ENV=development, flask run)

What I should see is Hello, World!

Instead, I’m presented with the following errors:

Traceback (most recent call last):
  File "/Users/David/Desktop/flaskr/venv/lib/python3.6/site-packages/flask/cli.py", line 330, in __call__
    rv = self._load_unlocked()

  File "/Users/David/Desktop/flaskr/venv/lib/python3.6/site-packages/flask/cli.py", line 317, in _load_unlocked
    self._app = rv = self.loader()

  File "/Users/David/Desktop/flaskr/venv/lib/python3.6/site-packages/flask/cli.py", line 372, in load_app
    app = locate_app(self, import_name, name)

  File "/Users/David/Desktop/flaskr/venv/lib/python3.6/site-packages/flask/cli.py", line 246, in locate_app
    'Could not import "{name}".'.format(name=module_name)

flask.cli.NoAppException: Could not import "flaskr.flaskr".

Simply, I’m not sure how I should respond to or work upon fixing an error like this. Perhaps I have a mismatch in what I have installed in the venv and what this particular project requires?

Like this person: Could not Import Pandas: TypeError

Flask:

  • /Users/David/Desktop/flaskr/venv/bin/Flask
  • Version: 1.0.2

Pip:

  • from /Users/David/Desktop/flaskr/venv/lib/python3.6/site-packages (python 3.6)
  • Version: 9.0.1

Python:

  • /Users/David/Desktop/flaskr/venv/bin/python
  • Version: 3.6.0

I think you are in the wrong folder. You probably did:

cd flask_tutorial/flaskr

You need to go up to the tutorial folder:

cd ..

You should flask run in the flask_tutorial folder rather than flask_tutorial/flaskr because you want to import flaskr from that folder, not flaskr/flaskr (which doesn’t exist).

Those running flask for the first time ..This works well for windows

find the location of your folder use cmd please ‘mine is cd /users/hp/Desktop’

cd /users/hp/Desktop>set FLASK_APP=hello.py -->file name
cd /users/hp/Desktop>set FLASK_ENV=development
cd /users/hp/Desktop>flask run

I just installed the latest versions of Flask and Werkzeug and everything was fixed:

python -m pip install Flask==2.0.1
python -m pip install Werkzeug==2.0.1

Notes:

  1. I did not use __init__.py
  2. I run flask app as:
set FLASK_ENV=development
set FLASK_APP=app.py
flask run --port 5000