In this guide i will go over the steps of getting an existing 8.x vRSLCM appliance upgraded to the latest 8.4 release. The release notes can be found here
The first step is to lo in to vRealize Suite Lifecycle Manager under the Lifecycle Operations section
Go to settings -> System Upgrade
Click on Check for Upgrade
We can see that the check found a new version available for 8.4
Click on Upgrade
This will fire up the upgrade process and start upgrading packages. The system will automatically reboot on 8.4 once completed. We can check the version by going to Settings -> System Details
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