Flask 'hello World' Not Working

I copy pasted the flask's 'hello world' app from their website and am trying to run it. I get an error message in Chrome saying Internal Server Error The server encountered an in

Solution 1:

I don't know why but when I change

app.run()

to

app.run(port=4996)

it starts working. No idea why the default port is throwing an error. Oh well.

Solution 2:

from flask importFlaskapp= Flask(__name__)


@app.route('/')
def index():
    return'Hello World'if__name__== '__name__':
    app.run()

app.run(port=5000)

Solution 3:

For Windows machines you can use the command in cmd:

set FLASK_APP=python_file.py
flask run

Solution 4:

Some other process is running on port 5000. It may be you still have an old Flask process running, with broken code. Or a different web server altogether is running on that port. Shut down that process, or run on a different port.

You can switch to using a different port with the port argument to app.run():

app.run(port=8080)

If you can't figure out what process is still bound to port 5000, use the Windows Resource Monitor or run netstat -a -b from a command line. See How can you find out which process is listening on a port on Windows?

Solution 5:

I think you are trying to copy the route generated through your flask program in cmd by pressing ctrl+c which quits your running flask program . i was also doing the same.just try to type the route generated by your flask program on your browser . it will definitely resolve your problem.