The negative underlying operating profit compares with a loss of SEK 117 million (€12 million) in the same three-month period of 2016.
Vattenfall said the loss was due to cable and grid outages for some of its offshore wind projects.
"In the wind business we are growing and adding new capacity, but during this typically low-wind quarter we had some issues with cable outages that negatively affected the production volume," Vattenfall's outgoing CFO Stefan Dohler said.
The state-owned firm, however, recorded a 56% increase in underlying operating profit in the first nine months of 2017.
Underlying operating profit totalled SEK 725 million (€74.6 million) in the period January to September this year, up from SEK 480 million (€49.4 million) in the same period of 2016.
The increase was put down to the additional wind capacity Vattenfall commissioned in the period.
In September, the firm completed its largest onshore wind project in the UK, the 228MW Pen y Cymoedd site.
Along with its third quarter results, Vattenfall has also announced a €200 million investment in the repowering and expansion of the Wieringermeer project in the Netherlands.
The 100-turbine Wieringermeer project in the north of the country was due to see 93 older turbines replaced with modern, higher rated machines.
At the end of September, Vattenfall increased its ownership of the turbines at the Wieringermeer site, which is part-owned by the Windcollectief Wieringermeer consortium, led by the energy research centre of the Netherlands (ECN).
As a result of the deal, Vattenfall will own 82 turbines (up from 50), while ECN will own 17 machines and a single turbine will be owned by local residents.
The project had been delayed after Dutch grid network firm Alliander said it would not be able to connect the new turbines until Q2 2019 at the earliest.
Vattenfall, through its Dutch subsidiary Nuon, is now targeting a 2020 completion date.
