Praise be to Allah, and may Allah’s peace and blessings be upon the Messenger of Allah, his family and his companions. Wa alaikum assalam wa rahmatullahi wa barakatuh. As to what follows: In response to your question, we say:   Having a wet dream during the day in Ramadan does not invalidate fasting, and the fasting is valid. This is because the ejaculation of semen by a sleeping person does not affect the validity of fasting.  All the nullifiers of fasting take the nullification ruling if a person does them by his own volition and choice. However, if this is not by choice then his fasting is not affected. The scholars had a consensus of opinion that a wet dream does not affect the validity of fasting, because a sleeping person is not responsible for his actions, and a wet dream occurs in sleep.