Without the pillars, Hajj is not valid. Whoever leaves an obligation still has a valid Hajj but owes a sacrifice (dam) according to the majority. Everything else is sunnah.
The steps
- The pillars according to the majority: ihram, standing at Arafah, Tawaf al-Ifadah, and sa‘i.
- The obligations: ihram from the miqat; staying at Arafah until sunset for whoever stands there in the daytime; staying the night at Muzdalifah; staying the nights of Tashriq at Mina; stoning the jamarat; shaving or shortening; and the farewell tawaf.
- The greatest pillar is standing at Arafah; whoever misses it has missed the Hajj.
The evidence
The Prophet ﷺ said: “Hajj is Arafah” (Abu Dawud 1949, al-Tirmidhi 889, narrated by Abd al-Rahman ibn Ya‘mar, graded authentic by al-Albani).
For the Hanafis, the pillars of Hajj are standing at Arafah and Tawaf al-Ifadah, and sa‘i is an obligation. Refer to your own school or scholar for your situation.