When you create a custom minimal.master it’s also required to have all the placeholders defined. We already know this from the v4.master but why are they needed when they are not used? They are necessary for the edit mode of the minimal masterpage. When you edit a minimal masterpage and you have only defined the minimal.master placeholder you get error messages like “Cannot find ContentPlaceHolder ‘PlaceHolderLeftNavBar’ in the master page '~masterurl/default.master', verify content control's ContentPlaceHolderID attribute in the content page.”
List of all the required ContentPlaceHolders:
