"ASX is very disappointed with today's outage and sorry for the disruption caused to investors, customers and other market users," managing director and CEO Dominic Stevens said yesterday.
The ASX and its technology provider Nasdaq said they had identified the root cause of the problem and would resolve it overnight before today's 10am opening.
Elsewhere, markets closed higher yesterday and futures were looking positive at the time of writing as data indicated China's economic recovery continues.
The copper price reached US$7,179 per tonne intraday on the London Metal Exchange, a fresh high not seen since June 2018, Marex Spectron's Alastair Munro said.
He also pointed to the political turmoil in Peru, where the interim president has resigned, and reports workers at the Candelaria copper mine in Chile were leaning towards rejecting Lundin Mining's latest wage offer, signalling a strike could extend into a second month.
The gold price is worth about $1,889 an ounce on the spot market.
Metals and mining equities gained about 2.6% in Toronto yesterday.
Dual-listed Condor Gold (TSX: COG), which is focused on its La India project in Nicaragua, closed up almost 17% after reporting on Friday it had received £62,000 through the exercise of warrants.
At the bigger end of town, Barrick Gold closed down 0.5%.
In the copper space, Freeport-McMoRan rose 4.22% in New York and Antofagasta gained 2.71% in London.