After scanning your 'sources.list' no valid entry for '%s' was found. Should default entries for '%s' be added? If you select 'No', the upgrade will cancel.
Wedi sganio 'sources.list' methwyd canfod cofnod dilys i '%s'. A ddylid ychwanegu cofnod '%s' diofyn? Os wnei di ddewis 'Na' bydd yr uwchraddiad yn terfynu.