Env. Variables not set while running Minimal Flask application

Question

I am trying to follow the flask documentation on my windows machine given at the following link: http://flask.pocoo.org/docs/0.11/quickstart/#debug-mode

Firstly I wrote the code below in a python script:

from flask import Flask app = Flask(__name__)  @app.route("/") def hello():     return "Hello World!"  if __name__ == "__main__":     app.run(debug=True) 

I saved this in a file called run.py

Then wrote this command in the command window:

set FLASK_APP = run.py  flask run 

Upon running this, I am getting the following error:

"Error: Could not locate flask application. You did not provide the FLASK_APP environment variable"

I was expecting to get this instead:

Running on http://127.0.0.1:5000/ 

Can somebody tell me how to fix this?

Answer 1

I faced the same issue while using PowerShell and that fix worked for me:
instead of using set FLASK_APP = run.py, try $env:FLASK_APP = "run.py"

Answer 2

If you are using powershell it does not works i dont know why please use cmd.exe since i use VScode editor it provide powershell as a terminal(ctrl + back-tick) by default so i was trying to run flask app on the powershell and it was giving me same response as you are getting

1. open cmd.exe (or if you are VSCode user like me simply write cmd on that terminal, or you can also press Ctrl + Shift + C to open a windowed cmd terminal)

2. set FLASK_APP=hello.py (without spaces, only for first run then it remember until restart of cmd)

3. flask run (or just flask will also work)

note: this is only for windows user