One may use bread for Kiddush if wine or grape juice are not available but may one use bread for havdallah when wine or grape juice are not available?
One cannot use bread for havdalah. If one has no wine or grape juice, one can use chamar medinah. (Shulchan Aruch Orach Chayyim 296:2)
4Unless Sunday is Yom Tov, then you can use bread– Double AA ♦Jun 20, 2019 at 11:06
2For other readers, what @DoubleAA implies is that when Yom Tov follows Shabbat, the Kiddush incorporates havdallah. As the "main" prayer is Kiddush, one may use bread for Kiddush.– DanFJun 20, 2019 at 14:17
This answer is definitive for Sephardim (as supported by @Yishai's comment above), does it hold for Ashkenazim as well?– יהושע קJun 20, 2019 at 16:44
Yes. The ruling of the Shulchan Aruch seems to be uncontested.– BigJohnJun 20, 2019 at 22:33