Tesla Chief Elon Musk said on Friday he was checking up on an app server outage that prevented many owners from connecting to their cars.

Musk was responding to a Tesla owner’s tweet that he was experiencing a “500 server error” when trying to connect to his Model 3 through the iOS app.

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About 500 users reported they faced an error at around 1640ET (2140 GMT) according to outage monitoring website Downdetector, which tracks outages by collating status reports from a series of sources — including user-submitted errors — on itsplatform.