Many Nigerians have once again been left without state-supplied electricity for hours on end, three weeks after the president apologised for the last nationwide outage.
A system failure on the national grid at about 18:30 local time (17:30 GMT) on Friday evening is to blame, distribution companies have said.
They have assured customers that work is underway to restore power. Local media report that this is the fifth such collapse this year, reports BBC.
Electricity providers - including Abuja Electricity Distribution, Kaduna Electric and Eko Electricity Distribution - took to social media to apologise and explain what happened.
The BBC's Ishaq Khalid in Abuja says Nigeria generates too little electricity to supply its population of 200 million people, generally hovering at around 4,000 megawatts a day.
Last month Nigeria's President Muhammadu Buhari said he deeply regretted the inconvenience caused to people across the country by simultaneous fuel shortages and a national power grid collapse.
At the time, he added that the government had worked "tirelessly" to fix problems at thermal stations, which had coincided with a "dip in hydroelectric generation due to seasonal pressures".
