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The management extension is required to manage policies used by the VSE 8.8 Patch 7 package on the endpoint.
Typically it is good practise to check in the management extension of any product prior to deploying the package to managed systems.
Can you confirm that you have modified the McAfee Agent > General Policy > Updates tab to get product updates from the Evaluation branch (where your VSE 8.8 Patch 7 package is checked in) prior to running the McAfee Agent - Product Update Client Task to upgrade the VirusScan version?
I went ahead and installed the extension to the latest version and yes I had done all the rest, such as changing the McAfee general policy to point at the evaluation branch.
All is good now.
Thanks for your correspondence