When you are upgrading to Deployment Manager 4.5.1 from 3.2.1 or later, manual post-upgrade steps are no longer required for either on-premises or Pega Cloud Services environments. After Deployment Manager upgrades, a health check is run on your system; after it passes, post-upgrade steps run automatically.
By eliminating manual post-upgrade steps, you can quickly upgrade to new versions of Deployment Manager with ease. Additionally, on cloud, you can continue to use Deployment Manager without data loss while the post-upgrade steps complete.
For more information, see Understanding model-driven DevOps with Deployment Manager.