What is the ruling on raising the hands before bowing and before completing the recitation of Al-Fatiha, and does this act invalidate the prayer?

The Sunnah is for the worshiper to raise his hands when performing the takbir for bowing (ruku'), and that is after completing the Fatiha or the Fatiha and a surah. The raising of the hands should coincide with the beginning of the bowing. As for raising them during the recitation of the Fatiha or a surah, it is an unprescribed act, but it does not invalidate the prayer because it is a minor action, and no prostration of forgetfulness (sujud sahwi) is required for doing it.