I will be in Kyiv in the fall. (should be a correct answer also.)
"In fall" actually sounds incorrect to my ears. "in autumn" or "in the fall" are the two natural sounding options.
Тим більше, що у підказці зазначено in the fall.
In fall, in the fall and in autumn are all accepted now.
Shouldn't the English spelling "Kiev" also be an acceptable answer? (In addition to Kyiv)
Kiev has been accepted as an answer in a previous sentence