Mavericks in Mac App Store shows install button without text and won't download I am trying to upgrade to OS X Mavericks from 10.7.5 but every time I click the install button in the Mac App Store, it looks like nothing is happening and now the button is all greyed out and I can't do anything.
You can enable the Debug menu by typing the following into Terminal:

defaults write com.apple.appstore ShowDebugMenu -bool true


You can then clear the cookies using the Clear Cookies option in the Debug menu.

In addition, you can reset the application using the Reset Application option.



You can disable the Debug menu using the following:

defaults write com.apple.appstore ShowDebugMenu -bool false