Three of the provinces were looking to make home advantage count in the first round of the BKT United Rugby Championship, while Leinster began their title defence away to the 10bet Lions.
Fit-again Ireland international Mack Hansen made his first appearance for Connacht since last October, as Stuart Lancaster's men kicked off the season against the DHL Stormers at Dexcom Stadium.
28-26 winners over Edinburgh in pre-season, Ulster welcomed the Scottish capital side to Affidea Stadium with eight debutants in the province's matchday squad.
Max Deegan captained defending champions Leinster for their season opener in Johannesburg, while Academy duo Todd Lawlor and Dylan McNiece stepped up for their senior debuts.
Kieran Brookes and Ben O'Donovan made their first starts for Munster when they hosted Glasgow Warriors, the clash drawing a crowd of 11,031 to Thomond Park.
