Unable to send or read private messages on frontend

Very pleased with the appearance of the highly anticipated feature personal messages.
But on one my site they do not work.
Help to solve a problem: at attempt of use of messages, there is an error 404.

Error 404 when you try to view the message.
Error 404 when trying to write a message to a user from the frontend.
Error 404 when viewing a new message.

At the moment I can only send a message from the admin panel. But it is impossible to read it from the frontend.

Ensure Private Message System within CB > Plugin Management is published and public. How are you trying to reach the new internal PMS model? Ensure you're not trying to use old UddeIM menu items if you were originally using UddeIM as those will not go to the new internal model. You can create menu items to the internal model by selecting Community Builder > Plugin menu type and selecting Private Message System for the Plugin.