You must upgrade your applications to the [latest supported runtime version](https://docs.cloud.google.com/appengine/docs/standard/lifecycle/support-schedule#python) to continue receiving security updates and be eligible for technical support. The process of upgrading an existing app depends on the runtime version that your app currently uses: - **Python 2.7 (first-generation runtime)** : You must migrate your app to the [latest supported Python version](https://docs.cloud.google.com/appengine/docs/standard/lifecycle/support-schedule#python). Python 2.7 has reached [end of support](https://docs.cloud.google.com/appengine/docs/standard/lifecycle/runtime-lifecycle#end_of_support) on January 31, 2024. Your existing Python 2.7 applications will continue to run and receive traffic. However, App Engine might block re-deployment of applications that use runtimes [after their end of support date](https://docs.cloud.google.com/appengine/docs/standard/lifecycle/support-schedule#python). To migrate from Python 2.7 to the latest supported version of Python, see [Migrate to the Python 3 runtime](https://docs.cloud.google.com/appengine/migration-center/standard/migrate-to-second-gen/python-differences). - **Python second-generation runtimes (after end of support)** : To upgrade to a [supported version of Python](https://docs.cloud.google.com/appengine/docs/standard/lifecycle/support-schedule#python), update the `app.yaml` file by specifying a version of Python that you want your app to run. For example: runtime: pythonVERSION Where VERSION is the Python `MAJOR` and `MINOR` version numbers. For example, to use the latest Python version, Python 3.15 (preview), specify `315`. For more information, see the [Python runtime overview](https://docs.cloud.google.com/appengine/docs/standard/python3/runtime).