I actually do have the same problem / question...
Bad value twitter:card for attribute name on element meta: Keyword twitter:card is not registered.
Bad value twitter:site for attribute name on element meta: Keyword twitter:site is not registered.
Bad value twitter:creator for attribute name on element meta: Keyword twitter:creator is not registered.
Bad value twitter:description for attribute name on element meta: Keyword twitter:description is not registered.
12 Errors resulting on using the meta card twitter option... :(