Neither - "cropped up" >> crop up - OneLook Dictionary Search
Student or Learner
I can't make it tonight. Some problems just popped out/up and I have to work over time.
Is it "popped out or up" in the above context? Thanks.
It can, but the idiom you need to use in the sentence you offered is "cropped up".
"The problem popped up again" is a possible use. "The cat popped up in the garden" - again, this is a possible use. But if something gets in the way of your plans, it is usually something that has cropped up
If you want your English to sound fluent, there are times when you will just have to accept an idiom as the one that is always used.
In America, I hear people say that something "popped up" far more frequently than I hear that something "cropped up."