Roblox’s safety update is locking some users out of chat, deleting old messages and pushing frustrated players off-platform.

The gaming platform poses both content concerns and safety risks that put minors in “the Devil’s crosshairs.” The company says tighter restrictions are coming.

Roblox said inappropriate content is rare and security has been increased. Over 54 million users play Roblox, a popular multiplayer online game, every day and nearly half of them are under the age of ...