The backup or replication job is processed slower than expected and gives the warning message “changed block tracking cannot be enabled: virtual hardware version 7 or later required."
The job works without Changed Block Tracking, and the “changed block tracking cannot be enabled: virtual hardware version 7 or later required” error can be seen in the job log.
The VM that is being backed up/replicated has virtual hardware version 4, which does not support changed block tracking.
You need to updarde the hardware version. To do so:
Start the vSphere Client or vSphere Web Client and log in to the vCenter Server
Power off the virtual machine
Right-click the virtual machine and select the menu option to upgrade virtual hardware
In vSphere Client, the option is Upgrade Virtual Hardware
In vSphere Web Client, the option is Configuration > Upgrade Virtual Hardware
The software upgrades the virtual hardware to the latest supported version.
Note: The Upgrade Virtual Hardware option appears if the virtual hardware on the virtual machine is not the latest supported version.
Click Yes to continue with the virtual hardware upgrade
Power on the virtual machine
Note: If the virtual machine has a Microsoft Windows guest operating system, the operating system detects a new device, configures the device, and prompts you to reboot the guest operating system. If any unknown devices are recognized, the operating system prompts you to configure the device manually.
For Windows guest operating systems, reboot the guest operating system to make the changes take effect.
For more information, refer to the VMware Knowledge Base at the link below: