I may have accidentally clicked the ‘Beta off’ button.
So i have disabled beta and i'm back to the old layout.
Where i can not reply to PMs for example, giving me an error like ‘failed to send message’.
And i can not turn on beta again. Clicking the button again (which still says ‘off’ not ‘on’, although it is already off) reloads the page but does nothing.
In case there is another to turn on beta mode i have not found it.