What is the ruling on performing ghusl for janabah or menstruation without washing braided hair?

This is a grave error and is impermissible. The prayer is invalid. Rather, it is obligatory to make the water reach all parts of the body, including the hair, whether it is for ghusl from janabah (ritual impurity), or purification from menstruation or postnatal bleeding, as narrated in the hadith of Umm Salamah (may Allah be pleased with her). If the hair is braided, it must be washed, and the water must reach its roots and wash whatever hangs down from it. Therefore, the prayers that were performed without properly washing the hair must be made up.