$ mux default
lost server
no server running on /home/$USER/.tmux.d/sockets/tmux-4211816/$USER
no server running on /home/$USER/.tmux.d/sockets/tmux-4211816/$USER
no server running on /home/$USER/.tmux.d/sockets/tmux-4211816/$USER
no server running on /home/$USER/.tmux.d/sockets/tmux-4211816/$USER
no server running on /home/$USER/.tmux.d/sockets/tmux-4211816/$USER
no sessions
Fix this ...