OSX Mavericks "This disk cannot be used to startup your computer"
I downloaded Mavericks through the app store and when I try to update I get "This disk cannot be used to startup your computer", therefore I cannot update.
Tried all of the usual things. Repaired drive etc.nothing was wrong.
All the advice I find on the net says I need to wipe the disk and do a clean install. Any way to avoid that?
MacBook Pro 10.6.8