According to the release notes for RU6MP1:
You cannot migrate to Symantec Endpoint Protection from all Symantec products.
You must uninstall the following products before you install the Symantec Endpoint
Protection 12.1.6 MP1 client:
■ The legacy Symantec products Symantec Endpoint Protection 11, Symantec
Endpoint Protection Small Business Edition 12.0, Symantec AntiVirus, and
Symantec Client Security
Does this mean that I have to uninstall SEP 11.x before upgrading to SEP 12Ru6Mp1 or can I still do an inplace upgrade?
I still have 4500 machines left on SEP 11.x to be upgaded.