The two pillars agreed upon as indispensable are standing at Arafah and Tawaf al-Ifadah (the tawaf of visitation), for the Prophet said, 'Hajj is Arafah,' and Allah commanded the pilgrims to 'circumambulate the Ancient House.' Most scholars, including the Shafi'is and Hanbalis, add the intention/ihram and the sa'i between Safa and Marwah as pillars, so that the well-known list is: ihram, standing at Arafah, Tawaf al-Ifadah, and sa'i. Whoever misses standing at Arafah in its time has missed the Hajj entirely and must repeat it, whereas Tawaf al-Ifadah remains a debt that must be fulfilled even if delayed, and cannot be replaced by a sacrifice.
Evidence — the daleel
On deen2u
Informational, not a personal fatwa. Consult a qualified scholar for rulings on your situation.