Facebook’s Instagram stopped working for about an hour for many users on Wednesday, with people getting such error messages as ‘Couldn’t refresh feed’ and ‘We’re sorry, but something went wrong. Please try again’ on the app.

The online version of the photo- and video-sharing networking service also didn’t work, showing the message ‘5xx Server Error.’

‘#instagramdown’ started trending on Twitter as well. It wasn’t immediately clear why the service had issues, reports hollywoodreporter.com.

Outage tracking site Down Detector showed that users in Europe, Australia and on the West Coast of the U.S. were particularly affected given the problems seemed to start just after midnight L.A. time. But around 1:15 a.m. L.A. time, the service was back up.

The outage comes at a time of change at Instagram. Co-founders Kevin Systrom and Mike Krieger recently resigned amid reported clashes with Facebook CEO Mark Zuckerberg, catching Wall Street by surprise. Facebook veteran Adam Mosseri on Monday was named the new head of Instagram. Facebook bought Instagram in 2012 for $1 billion.