I saw that the buildings in Cairo were decorated at night with what resembled Ramadan decorations, and the people began to hang decorations in preparation for the appearance of the Mahdi. The people did not know who the Mahdi was, but they knew that he would appear. I saw the people at the top of one of the buildings hanging the last of their decorations, as if Cairo had been completely decorated with sunrise, and all that remained was the appearance of the Mahdi. After that, I woke up to the dawn call to prayer.

O God, make this vision a true vision and hasten the appearance of the Mahdi soon and make us among his soldiers and make us among the third martyrs in his conquests

Update
Some comments indicated that adornment was mentioned in the Qur’an not as a sign of good news, but rather as a warning of an event that would occur.
(Until, when the earth has taken on its adornment and is beautified and its people think that they have power over it, Our command comes to it by night or by day, and We make it as a harvest, as if it had not flourished yesterday.)
(Your appointment is on the Day of Adornment, and when the people will be gathered together at noon.)
May God protect us all

Interpretation of the vision in this video