Flight QF82 was due to depart Changi Airport at 8:45 p.m. on July 14 but was canceled after engineers discovered a technical fault, the Brisbane Times reported.
Passengers were told to disembark around midnight and later sent to hotels after being informed the plane could not fly.
Qantas initially planned to fix the A380, but the airline later admitted the problem required "extended maintenance." Passengers received a written update saying the aircraft would not operate as planned and that a replacement jet would be flown in from Australia.
By July 16, many travelers had been stranded for nearly three days, with multiple promised departures delayed or canceled. Some were told to expect a flight on the morning of July 16, only for it to be canceled again.
Qantas has apologized for the prolonged disruption, adding that an A330 had been flown from Australia to help get customers on their way as quickly as possible.
Affected passengers were offered hotel stays and reimbursement for "reasonable" out-of-pocket expenses, including meals, The Straits Times reported.
The replacement aircraft was expected to depart Singapore on the night of July 16, arriving in Sydney the next morning, according to the airline.
Changi Airport data showed Flight QF82 was scheduled to depart at 8:45 p.m. on July 16 for Sydney. A separate Qantas service, QF2, was also delayed until 11:20 a.m. on July 17.
The double-decker Airbus A380 can carry over 500 passengers in its typical three-class setup.