python - Running Flask app on Windows raises "an operation was attempted on something that is not a socket" -

when running basic flask app getting error in shell , can't find how solve this.

 running on http://127.0.0.1:5000/ (press ctrl+c quit) <br/>  restarting stat<br/>  debugger active!<br/>  debugger pin code: 295-257-376<br/> exception in thread thread-1:<br/> traceback (most recent call last):<br/>   file "c:\users\admin\appdata\local\programs\python\python35-32\lib\threading.py", line 923, in _bootstrap_inner     self.run()<br/>   file "c:\users\admin\appdata\local\programs\python\python35-32\lib\threading.py", line 871, in run     self._target(*self._args, **self._kwargs) <br/>   file "c:\users\admin\appdata\local\programs\python\python35-32\lib\site-packages\werkzeug\serving.py", line 656, in inner     fd=fd)<br/>   file "c:\users\admin\appdata\local\programs\python\python35-32\lib\site-packages\werkzeug\serving.py", line 550, in make_server     passthrough_errors, ssl_context, fd=fd)<br/>   file "c:\users\admin\appdata\local\programs\python\python35-32\lib\site-packages\werkzeug\serving.py", line 462, in __init__     socket.sock_stream)<br/>   file "c:\users\admin\appdata\local\programs\python\python35-32\lib\socket.py", line 446, in fromfd     nfd = dup(fd)<br/> oserror: [winerror 10038] operation attempted on not socket 

from flask import flask, render_template  app = flask(__name__)  @app.route('/') def main():     return render_template('main.html')  app.run(debug=true) 

you're trying execute global python installation. "good practice" use virtual environments python projects keep each projects' pip install separate.

start running pip install virtualenv

then, navigate projects folder , execute virtualenv example-virtual-env. create new folder own python , pip installation. (it supports virtual environments python 3 well.)

now in shell, execute <projects_folder>\scripts\activate activates virtual environment. every pip install execute within environment (note environment name before shell cursor.)

in here, run pip install flask , run flask application.

if you're still experiencing issue, try running cmd in administrator mode.