Users around the world, on both iOS and Android, have been unable to log into the app at all on on Tuesday. Those fortunate enough to open the program could not send or receive messages. The cause of the outage is unknown.

On Monday, Facebook announced that it would be restricting the amount of messages users can forward, ostensibly to improve privacy and security.

"Starting today, all users on the latest versions of WhatsApp can now forward to only five chats at once, which will help keep WhatsApp focused on private messaging with close contacts,” the company said. “We'll continue to listen to user feedback about their experience, and over time, look for new ways of addressing viral content.”

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