Issue with Werkzeug library

Posted May 18, 2021 627 views
PythonUbuntu 20.04Flask

Hey everybody,

My code works perfectly fine on my machine, but when I deploy it to Ubuntu server (Ubuntu 20.04 (LTS) x64) I get the following error:

(env) root@ubuntu-s-1vcpu-1gb-intel-nyc1-01:~/demo# python

  • Serving Flask app “demo” (lazy loading)
  • Environment: production WARNING: This is a development server. Do not use it in a production deployment. Use a production WSGI server instead.
  • Debug mode: on
  • Running on all addresses. WARNING: This is a development server. Do not use it in a production deployment.
  • Running on (Press CTRL+C to quit)
  • Restarting with stat Killed (env) root@ubuntu-s-1vcpu-1gb-intel-nyc1-01:~/demo# * Debugger is active!
  • Debugger PIN: 521-632-002 Traceback (most recent call last): File “/root/demo/”, line 4, in <module>‘’) File “/root/demo/env/lib/python3.8/site-packages/flask/”, line 990, in run runsimple(host, port, self, **options) File “/root/demo/env/lib/python3.8/site-packages/werkzeug/”, line 1000, in runsimple rwr( File “/root/demo/env/lib/python3.8/site-packages/werkzeug/”, line 418, in runwithreloader ensureechoon() File “/root/demo/env/lib/python3.8/site-packages/werkzeug/”, line 398, in ensureecho_on termios.tcsetattr(sys.stdin, termios.TCSANOW, attributes) termios.error: (5, 'Input/output error’)

What could be the problem?

Thank you so much for your help!

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1 answer

Not entirely sure of what might cause this, but input/output error might have to do with permissions. Is this writing to the terminal or a (virtual?) serial port?

In the latter case, make sure you are added to the correct group (modem, I believe, then logout and login again).

In the former, check who owns the python script you’re trying to run.
Go to the folder where is located and run ls -lh
Try running as root (sudo python to see if it fixes it.

If it works under sudo, it is most likely a permissions issue.

If you’ve uploaded the file as root, then the regular user may not be allowed to run the script (just a thought).