The advantage of owning a Tesla is using your smartphone as a key to open and drive your car as there is no need to carry a separate key fob in your pocket. But what if your smartphone app glitches? You could be stuck not being able to use your car, which seems to be happening to Tesla owners around the world.

On Friday a number of social media users reported getting a “500 server error” when trying to use the Tesla app. That indicates something has gone wrong with an Internet server the app is trying to connect.

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“Still stuck in Seoul” wrote Jaehwan Cho on Twitter after earlier reporting the server error when trying to use it with his Tesla Model 3.

According to Downdetector, it showed a large spike in reported Tesla server problems at around 5pm on Friday. However, it is unknown exactly how many Tesla owners are affected by the outage, or how many are locked out of their cars.

Tesla, which hasn’t engaged with professional news media for over a year, did not respond to a request for comment.

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Tesla cars also come with a key card that works like the wireless key fob many vehicles have today. So in a pinch, Tesla owners can still use that to get into their cars and start them.

If properly set up, the phone can also connect directly to the car without going through the Internet server. But drivers who relied solely on the app using an Internet connection were stuck.

The smartphone app also shows things like the car’s level of battery charge and whether it’s charging.