The Python 3.4 runtime for the App Engine flexible environment was shut down on March 29, 2019.
Starting on this date, new deployments to the App Engine flexible environment that request Python version 3.4 fail. You must update to a newer version of Python to help you avoid security risks that may result from the end-of-life of Python 3.4 by the Python language community.
Migrate to a new Python version
To migrate to a newer Python version, follow these steps:
Update the Cloud SDK with the latest updates by invoking the
gcloud components update
app.yamlfor all versions of your application as follows:
runtime_config: python_version: 3
3means use the latest available Python version. Specify
3.5to use Python
3.6to use Python
Deploy your application. This is required to pick up the new changes.
Where to get help
If you run into any trouble migrating your application, and you have a support package, you can get help through your normal support channel. If you don't have a support package, respond to the email that you received notifying you about the deprecation of Python 3.4.