The pulp, paper and packaging board maker - one of the largest globally - warned that demand growth is forecast to slow across its businesses and the decline in demand for paper would continue in Europe.
While the shift to online reading has reduced the need for newspaper and magazine paper for years, growth in ecommerce has increased the usage of shipping boxes and packaging materials.
But research firm Fastmarkets said that boost was beginning to fade with the biggest online companies focusing on using less packaging after a rise in corrugated and containerboard prices in the last few years.
Stora Enso forecast an adjusted operating profit of 100-180 million euros in the fourth quarter as prices for pulp and paper weaken, missing all analyst expectations which ranged from 182 million to 315 million euros, according to Refinitiv data.
"Deteriorating trading conditions caused by geopolitical uncertainties related to trade wars and a possible hard Brexit are expected to impact Stora Enso negatively," said Chief Executive Karl-Henrik Sundstrom.
The company's shares fell almost 9% before recovering some losses, with European paper and packaging firms UPM, Svenska Cellulosa, Metsa, Mondi and Holmen all down by as much as 4%.
UPM had last week reported better than expected profits for the September quarter saying it had seen modest demand growth in most areas.
Stora Enso reported a sharp drop in profit in the three months to September, with adjusted operating profit in the third quarter falling 35% from a year earlier to 231 million euros (£200 million) and missing the average forecast of 236 million in a Refinitiv analyst poll.
Sales in July-September fell 7% from a year earlier to 2.4 billion euros, missing a forecast of 2.51 billion euros.
Antti Viljakainen of equity research firm Inderes said in a note that the weak outlook would pressure the company in 2020.
Stora Enso said it would increase its cost cutting target to 275 million euros from 200 million to battle slowing demand.
"The boxboard industry faces challenges in terms of fiber costs, sales growth, operating rates, and profits," Fastmarkets analyst Ken Waghorne said in a statement earlier this month.
(Reporting by Tarmo Virki and Anne Kauranen; Editing by Tom Hogue and Kirsten Donovan)
By Anne Kauranen and Tarmo Virki