72nd session of UN General Assembly held on?

The correct answer is September 12 to 25, 2017.
The 72nd Session of the United Nations General Assembly (UNGA 72) officially opened on September 12, 2017. While the session technically continues for a full year, the "high-level" portion—which includes the famous General Debate where world leaders speak—concluded on September 25, 2017.

Leadership and Theme:

The session was presided over by Miroslav Lajčák, the Minister of Foreign and European Affairs of Slovakia. Under his leadership, the assembly focused on a humanitarian and planet-centric approach.
The official theme was:

                           "Focusing on People: Striving for Peace and a Decent Life for All on a Sustainable Planet."

Key Highlights of the 72nd Session:

• António Guterres' First Session: This was the first General Assembly session for António Guterres as the UN Secretary-General.


• UN Reform: A major push was made to reform the UN's peace and security architecture to make the organization more responsive to modern conflicts.


• Global Issues: The session was dominated by discussions on the nuclear threat in North Korea, the Syrian conflict, and the migration crisis.