German Chancellor Angela Merkel will miss the opening of the G20 summit in Argentina after her plane was forced to make an emergency landing in Cologne due to a technical problem, her spokesperson said.
"We will not be proceeding today," she said.
Ms Merkel called the incident a "serious malfunction". She and German Finance Minister Olaf Scholz resumed their travel to Buenos Aires this morning, but they will arrive after G20 leaders start their discussions.
A senior journalist with the public national television ZDF said Ms Merkel would spend last night in Bonn.
The plane turned back from the Netherlands and landed in Cologne because it was the only base with a replacement aircraft, the DPA news agency said.
It was met on the tarmac by fire engines, DPA said, adding that the captain told the passengers the plane would have to turn back as a technical problem was disrupting several electrical systems.
Der Spiegel magazine said the government plane's entire communication system malfunctioned, constituting a serious emergency, with the crew forced to plan the landing using an on-board satellite phone.
A German Air Force spokesperson said that a failure of the electronic distribution box was the reason for the unscheduled landing.