Explanation
One of the potential causes of a failed install when upgrading Panorama to PAN-OS is having outdated plugins. Plugins are software extensions that enable Panorama to interact with Palo Alto Networks cloud services and third-party services. Plugins have dependencies on specific PAN-OS versions, so they must be updated before or after upgrading Panorama, depending on the plugin compatibility matrix2. If the plugins are not updated accordingly, the upgrade process may fail or cause issues with Panorama functionality3. References: Panorama Plugins Upgrade/Downgrade Considerations, Troubleshoot Your Panorama Upgrade, PCNSE Study Guide (page 54)