We took our old Swedish cash with us on trip there last summer only to find that it had “expired”. That is so strange. In the US, you could spend cash or coin from 100 years ago and it would still be valid. Of course, it’s probably worth far more than its face value as a collector’s item, so spending it wouldn’t make much sense, but you could.
That said, we didn’t need cash anywhere in Sweden. Card was so much easier. We eventually got some cash in Finland for use at a street fair. We were able to use it up, but other than that street fair, we probably could have done the whole trip without cash.