Hi,
you can check that KB: http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=2031711
Also you can update now without uninstalling Mirage (the KB is for Mirage 4.x which was not able to do a inplace update).
Mirage 5.4 is since last week released. Maybe this is also a option for you.
Best regards
Felix