I canned butter the other day, it was easy.
I canned butter two or three years ago and finally used it, some was 1 1/2 years old. It was all fine and tasted as it did when I canned it. It’s not exaclty like fresh butter but works well especially for cooking.
I prefer to make ghee and can that. But actually I’m planning to buy a lot of butter soon and can up a bunch of both.