From 1993 to 2019, the Department of Political and Peacebuilding Affairs (DPPA) (then Department of Political Affairs) provided backstopping support and guidance to the Personal Envoy of the United Nations Secretary-General for talks aimed at resolving the name dispute between Greece and, at the time, the former Yugoslav Republic of Macedonia (fYROM). Since 1999, the negotiations were convened under the auspices of Personal Envoy of the Secretary-General Mr. Matthew Nimetz, who succeeded Mr. Cyrus Vance.
On 12 February 2019, the entry into force of the “Prespa Agreement”, which was signed on 17 June 2018 and ratified by the legislature of both countries in January 2019, settled the longstanding dispute between Athens and Skopje on the “name issue”. The historic text details, inter alia, the parties’ agreement to the name “Republic of North Macedonia”. The Secretary-General informed the Presidents of the Security Council and the General Assembly, in identical letters, of the entry into force of the Agreement on 12 February 2019. The Secretary-General underscored that this resolution of the dispute demonstrated that even seemingly intractable issues can be resolved through dialogue and political will.
Have a look at the timeline of the process: https://dppa-ps.atavist.com/whats-in-a-name-for-north-macedonia-26-years-of-mediation