WhatsApp went down for its 2 billion users earlier today. Service issues started at around 4PM ET and prevented WhatsApp users from sending or receiving messages on the service for nearly an hour.

The WhatsApp application would still open, but a connecting loop was displayed while the service experienced issues.

Facebook-owned WhatsApp rarely experiences service outages, and this is the first major outage for more than a year. WhatsApp went down alongside Instagram and Facebook last year for around two hours, before service was restored.

Facebook revealed earlier this year that WhatsApp now has 2 billion users, up from 1.5 billion and 1 billion users in 2018 and 2016, respectively. The chat app is popular across many countries in Europe and in India and Brazil.

In a statement to The Verge, WhatsApp commented that “We’re aware that some people are currently having trouble sending messages and we’re working to restore WhatsApp for everyone as quickly as possible.”