If the automatic update process fails, you can upgrade the IaaS components separately.
If the vRealize Automation IaaS Web site and Manager Service successfully upgraded, you can run the IaaS upgrade shell script again without reverting to the snapshots you took before the upgrade. Sometimes a pending reboot event generated while upgrading multiple IaaS components installed on the same virtual machine can fail the upgrade. In this case, try manually rebooting the IaaS node and rerunning the upgrade to fix the problem. If the upgrade fails consistently, contact VMware support or attempt a manual upgrade by following these steps.
Revert your vRealize Automation appliance to its pre-update state.
Run a command to exclude the IaaS components from the update process. See Exclude Management Agents from Upgrade.
Run the update process on the vRealize Automation appliance.
Update the IaaS components separately using the Upgrade Shell Script or the vRealize Automation 7.3 IaaS installer msi package.