Definition: (referring to a problem or issue) to occur, or to be mentioned or discussed.
(This phrasal verb has more than one meaning)
E.g.1: Sorry I missed the celebration – a problem came up at the office and I had to work late.
E.g.2: Dave? You know I promised to give you a lift to the airport tonight? Well, something’s come up. I’m sorry, mate, but I won’t be able to do it.
This phrasal verb can’t be separated.