https://bugzilla.redhat.com/show_bug.cgi?id=920025
--- Comment #5 from Parag pnemade@redhat.com --- Currently yum groups behaviour is broken in Fedora 20 due to removed language support groups and yum started using groups as objects now. The better solution can be provided is to stop reporting this as a error and have some more meaningful informative message like "Due to comps cleanup %s group got removed and no longer exists. Therefore only setting the default system language".