python - set FLASK_DEBUG=1 not working on Powershell

Question

I'm building a Flask application and my file "helloworld.py" is:

from flask import Flask
app = Flask(__name__)

@app.route('/home')
def hello_world():
    return 'Home!'

@app.route('/about')
def about_us():
    return 'aboutus!'

My Flask code after activating venv:

set FLASK_DEBUG=1
flask run

Changes made to my "helloworld.py" file doesn't get automatically updated. I still have to restart it manually as I change anything in the code.

There is no error thrown but the changes simply don't reflect in the browser. Why is the debug mode not working, can someone help me out?

Answer 1

The syntax for setting environment variables is different in PowerShell. And for Flask 1.0 and higher, you should set FLASK_ENV instead.

$env:FLASK_APP = "helloworld.py"
$env:FLASK_ENV = "development"
flask run