Users of satellite navigation systems around the world were experiencing problems this week after Russia’s Glonass satellite positioning system was hit by a major disruption.

So far, the cause of the problem is a mystery. It started around 9 p.m. GMT (5 p.m. Eastern Time) on Tuesday, when most of the 24 satellites that make up the Glonass constellation began broadcasting erroneous data about their locations. The ability of satellite positioning receivers to provide an accurate fix is tied to the accuracy of the signal from space, so the problem immediately affected users.

“We could see this happening all over the world,” said Drew Davies, an operations executive at Canadian geo-services company Rx Networks and one of the first to spot the problem.

The U.S.’ Navstar Global Positioning System (GPS), the best known system for navigation, was not directly affected. But many modern GPS receivers and smartphones also rely on Glonass signals for an accurate location fix, so the Russian glitch caused problems well beyond that country’s borders.

The issues would have affected “urban canyons,” for instance, or streets bordered by high-rise buildings that block out most of the sky. “If you can only see three GPS satellites, your phone might use a couple of Glonass satellites to get a location,” Davies said.

While smartphone users had to put up with errors, some professional users were able to minimize the disruption.

“If you are unable to get a fixed position, deactivate the Glonass satellites on [your] receiver,” Belgian geo-services company Coudere told its users.

A status graph on the website of Russia’s Federal Space Agency confirmed the error impacted all Glonass satellites at some point, with the system finally returning to full health around 11 hours after the trouble began.

Despite the widespread disruption, the space agency has yet to provide details about what caused it.

“The likelihood is that bad ephemeris data was uploaded,” said Davies, referring to the celestial data that satellites use to determine their position.

Satellite navigation systems are vitally important to the global economy. The logistics industry relies on satellite navigation to manage the global flow of goods, aircraft use it for navigation, and deep-sea oil rigs use it to maintain their position at sea. The time signals they provide also help numerous automated systems stay accurate.