Power has been mostly restored to Indonesia's capital Jakarta, and nearby cities, 12 hours after a huge blackout began on Sunday.
The outage hit tens of millions of people, and Jakarta's newly-opened metro system was evacuated. Mobile phone networks were also affected.
The failure was caused by technical issues, state power company PLN said.
Nearly 10 million people live in Jakarta, and some 20 million in the surrounding cities.
Outages also hit neighbouring provinces, home to tens of millions more.
The disruption began at midday on Sunday local time and power was slowly being restored nine hours on.
Blackouts are a frequent occurrence in Jakarta, but Sunday's outage was unusually long.
The city's international airport was unaffected, while hospitals used backup power generators.
Traffic lights switched off in some areas of the capital, however, worsening congestion in a city notorious for traffic.
Ella Wasila, a commuter train passenger, told AFP: "The train stopped all of a sudden, we had to wait for a long time... There were so many babies in the coach, they were crying, and people were shouting 'open the door'."