A reddit post by u/Huntstark17 warns PS4 users to set their messages to private to prevent cryptic messages from entering to their inbox. The message bricks your console and forces you to reset your PS4 to factory setting. Hunstark17 was playing Rainbow 6 Siege where a player from the opposing side used a dummy account to send the message to his team which resulted to the crash. All of them had to issue a factory reset except from their teammates who set his messages to private.
Huntstark was able to get a screenshot of the message from a friend. The messages contains an unknown emoji/symbol which seems to be the cause of the glitch. For some users, just receiving the notification may sometimes be enough to force a reset. As of writing, there’s no update patch yet from Sony to solve this problem. To avoid this, the user must set their messages to PRIVATE.
Go to Settings > Account Management > Privacy Settings > *input your password* > Personal Info > and set Messages to either Friends or No One.
If you’re already affected, it’s not too late. Some user reports that issuing a factory reset doesn’t work as the moment they log in at PSN causes it to brick once more. Users may need to delete the message in the app as well as logging in another PSN account to make sure. And as an additional safety measure, you may need to change your hard drive or delete some users from your friendlist.