I reported this, but it might be worth mentioning here too. I answered "It goes upward" and was told I am almost correct.... should use "upwards." As far as I can determine, "upward" and "upwards" are synonymous. The same is true of "backward" and "backwards." [Some sources do make a fine distinction though. As an adjective... upward; as an adverb... upwards. But other sources I've checked do not make that distinction. ]
It’s a vague distinction, but uppåt means ’in the direction upwards (usually without a specific goal) and uppför means the same thing, but when you’re walking along something, like stairs or a hill. It’s commonly used with words like klättra (climb), because then you’re in contact with what you’re climbing, i.e. you’re going along the mountain for example.