Reference: Fataawa al-Lajnah ad-Daa.imah lil-Buhooth al-‘Ilmiyyah wal-Iftaa. – Fatwa No.7790
Fataawa Ramadhaan – Volume 2, Page 442, Fatwa No.368
Question: In one of the days in Ramadhaan, whilst fasting I went to sleep and had a wet dream. What is the ruling regarding this, and do I have to make an expiation?
Response: One who has a wet dream whilst fasting or in a state of ihraam for Hajj or ‘Umrah has no sin upon him nor any expiation and this act will have no [negative] baring on his fast, Hajj or ‘Umrah. He must perform the ghusl accorded to the major impurity if he excreted any sperm as a result.
And with Allaah lies all the success, and may Allaah send prayers and salutations upon our Prophet Muhammad ﷺ and his family and his companions.