About a third of the workforce is aged 15 to 29, a youth bulge that could bring Indonesia, a country of 250 million people, the sort of demographic dividend China and South Korea enjoyed a generation ago - but only if there are jobs for the 2 million people joining the workforce every year.
"The government doesn't have a blueprint for labor absorption," said property businessman Hariyadi Sukamdani, chairman of the Indonesian employers' association.
"If this condition is allowed to continue, what we would get is not a demographic bonus, but a demographic disaster. There could be social turmoil and higher crime rates."
Jobless in Jakarta
When he took office eight months ago, Widodo said he would pour billions of dollars into infrastructure and foster growth in manufacturing.
But the promised splurge on roads, power plants and ports has not materialized, largely because of bureaucratic hold-ups and land disputes, and a shortage of skilled labour is holding back growth in value-added industries.
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Miners have been hammered by a double whammy: a ban on mineral ore exports and a sharp drop in commodity prices.
Meanwhile, labor-intensive industries such as textiles and manufacturing have been hit by the rupiah's slide to a 17-year-low, which has raised the cost of imported raw materials.
Hundreds of redundant garment factory workers protested for hours this week in the financial district of Jakarta, the capital, after their company was declared bankrupt and its assets seized by two banks.
Unemployment in turn is hitting consumption, which makes up more than half of Indonesia's economy. Automobile sales in May fell 18.4 percent from a year earlier, the ninth decline in a row.
"Stocks are piling up because nobody is buying. The people's purchasing power is weak," said Ade Sudrajat, head of Indonesia's textile association. "This has never happened before in the last 45 years."
Arif Budimanta, adviser to the finance minister, said the government was introducing measures such as halving lending rates for small businesses and exempting most goods from a luxury tax to stimulate consumption.
At job fairs in Jakarta the gloom is palpable.
Naomi Octiva Naibaho, a manager at the Kompaskarier.com portal that ran one such fair recently, said about 6,000 jobseekers turned up every day, roughly triple the number of positions on offer.
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Gita Harahap, 26, has been sending resumes for weeks since the bank where she worked as a teller started a round of lay-offs, but she has had no luck. "No one has called me back," she said. "The competition is tighter."
In the first five months of this year, 79 companies approached Universitas Indonesia for potential recruitment, down from 110 over the same period of 2014, said Sandra Fikawati, head of the university's career development center.
The slowdown is also affecting higher-paid jobs, including in financial services, said Rob Bryson, Indonesia country manager for recruitment firm Robert Walters.
From mid-2013 to late last year, the number of foreigners holding work permits in Indonesia is estimated to have dropped 20 percent to around 62,000, partly because expatriate jobseekers saw more opportunities in Western countries, he said.
"Companies here are looking to increase productivity," Bryson said. "They will happily hire one person and let go of two in many circumstances, so that adds pressure to the employment scene."