You must upgrade your applications to the [latest supported runtime version](https://docs.cloud.google.com/appengine/docs/standard/lifecycle/support-schedule#go) 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: - **Go 1.11 (first-generation runtime)** : You must migrate your app to the [latest supported Go version](https://docs.cloud.google.com/appengine/docs/standard/lifecycle/support-schedule#go). Go 1.11 has reached [end of support](https://docs.cloud.google.com/appengine/docs/standard/lifecycle/runtime-lifecycle#end_of_support) on January 30, 2024. Your existing Go 1.11 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#go). To migrate to the latest supported version of Go, see [Migrate from Go 1.11 to the latest Go runtime](https://docs.cloud.google.com/appengine/migration-center/standard/migrate-to-second-gen/go-differences). - **Go second-generation runtimes (after end of support)** : To upgrade to a [supported version of Go](https://docs.cloud.google.com/appengine/docs/standard/lifecycle/support-schedule#go), update the `app.yaml` file by specifying a version of Go that you want your app to run. For example: runtime: goVERSION Where VERSION is the Go `MAJOR` and `MINOR` version numbers. For example, to use the latest Go version, Go 1.27, specify `127`. For more information, see the [Go runtime overview](https://docs.cloud.google.com/appengine/docs/standard/go/runtime).