Surprisingly enough, still a bug, though the error message is less cryptic these days. Basically the kdb_init_hist() in lib/kadm5/srv/server_kdb.c expects that the history principal has a key of the same enctype as the master key, which isn't necessarily the case, especially where master_key_enctype is not in supported_enctypes. The process of creating the history principal uses supported_enctypes, just like all of libkadm5's principal creations do by default. The creation of the history principal should probably explicitly use the master key's enctype.