Ask questionsDebugging with Flask does not work

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Environment data

  • VS Code version: 1.39.2
  • OS and version: Windows 10 x64
  • Python version: Python 3.7.3 / Anaconda 3
  • Type of virtual environment used: Continuum Anaconda virtualenv, also with base conda

Expected behaviour

Few weeks ago, I could run the flask debugger from my

Actual behaviour

This run is not possible showing the following error: "flask\", line 742, in _validate_key is_context = isinstance(cert, ssl.SSLContext) AttributeError: 'NoneType' object has no attribute 'SSLContext'"

Steps to reproduce:

Please find attached the gif with 3 simple steps flask_debugging_issue

Thanks in advance, kind regards, Germán


Answer questions kimadeline

Hi @GermanCM 👋 Thank you for reaching out! I can see you've been redirected here from

I couldn't replicate the issue when following the VS Code Flask tutorial like the original poster and with this setup:

  • macOS 10.14.6
  • Python 3.7.4
  • Anaconda 2019.10 for Python 3.7 (conda 4.7.12)

Do you have a sample project I could use to try and reproduce this issue? Could you also answer the following questions:

  • Which version of the Python extension are you using?
  • Does debugging work if you downgrade the extension?
  • Does debugging work if you use a non-conda virtual environment (venv, pipenv)?
  • Could you paste the output for Python in the Output panel (ViewOutput, change the drop-down the upper-right of the Output panel to Python)?


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