You deployed a new App Engine version and must immediately revert to the previous version. What should you do?

The correct approach is to route 100% of traffic to the previous, stable version on the App Engine Versions page. App Engine allows you to manage multiple versions of your application simultaneously. By directing all traffic to the older, working version, you effectively revert the deployment without needing to redeploy any code. "Run gcloud app restore" is not a valid gcloud command for App Engine. "On the App Engine page in the Console, select the app and click Revert" is incorrect because there isn't a direct "Revert" button for an entire application on the main App Engine page; reversion is handled at the version level. "Deploy the original version as a separate application and split traffic so the original serves 100%" is inefficient and unnecessary; you already have the previous version deployed and available.