The National Lottery App crashed as hopeful punters went to check if they won the mega €190million jackpot.
Lotto players across Ireland were left frustrated as they tried to scan their tickets on Tuesday night.
A Lotto spokesman confirmed the App was experiencing "technical difficulties".
He said: "We are currently experiencing technical difficulties. Our website and app are currently offline.
"We are working to restore normal functionality as soon as possible."
A UK punter scooped the monster top prize in main draw.
The lucky Lotto player became only the fourth person ever to claim the record-equalling windfall.
The punter became an instant multi-millionaire after matching five numbers plus two lucky stars in the main draw.
The winning numbers were 7, 10, 15, 44 and 49 and the lucky stars were 3 and 12. The jackpot, which had reached its cap, was rolling over for an unprecedented fifth time.
Meanwhile, a player in Ireland is €500,000 richer after scooping the top prize in the Plus draw.
The golden ticket, which was sold in Dublin, matched winning numbers of 4, 5, 14, 15 and 16.
Over 203,000 people in Ireland won prizes.
The most any Irish player won in the main draw was €3,800 - after they matched four numbers and two stars.
Four players outside of Ireland will take home €5.23million after matching five numbers and one lucky star.
The winning Ireland Only Raffle numbers were I-HCH-61199, I-HCK-09713, I-HCN-09503, I-HCN-22242, I-HCQ-37934, I-HCR-31998, I-HDB-83199, I-HDF-18755, I-HDF-42066 and I-HDG-96747. Each winner will pocket a cool €5,000.
