In it, 56-year-old Branko Djuric told the world he was sorry for doubting his newly-graduated son's ability to complete his higher education.
"I apologise to my son Ilija Djuric for not believing that he could pursue a degree at the faculty of electrical engineering," said the notice published at the weekend in the daily Politika.
The apology was widely shared and discussed on social media in the Balkan country.
"Ilija Djuric, you're my hero of the day," said one Facebook user.
More From This Section
Seeing Ilija struggle in his first year at university, Branko Djuric, 56, told his son he thought he would be unable to finish his studies, the father explained to local media following the advertisement.
"I told him, if you get your diploma I will apologise publicly," he said.
As promised, when his son officially became a telecommunications engineer, Djuric contacted the advertising department at Politika.