Police in the German city of Potsdam have carried out a controlled explosion on a device filled with nails next to a Christmas market.
The device, that also held batteries and wires, was sent to a pharmacy in the city south-west of Berlin.
Police initially said they found explosives inside, but later said there was no detonator.
Last December, 12 people died when an Islamist attacker hijacked a lorry and drove it at a Berlin Christmas market.
The device was found near Brandenburgerstrasse in the centre of Potsdam, which has a number of other Christmas markets.
A police spokesman said an X-ray scan was conducted on the device, which found that it had nails inside.
The Interior Minister for Brandenburg, Karl-Heinz Schröter, said police were searching the area in case more devices were sent, he said.
More than 2,600 Christmas markets opened across Germany on Monday. They bring in an estimated £2bn (€2.3bn; $2.7bn) of business a year.
The BBC's Damien McGuinness, in Berlin, says that there is an increased police presence in city centres this year, and that car barriers have been put up around some Christmas markets.
Germany's interior ministry said this week that the risk of an attack on its territory or in Europe was "continuously high".