After upgrading to tmux 2.9 this week our standard .tmux.conf produced the error invalid option: window-status-current-bg.
Our updated version is using “window-status-current-style” instead and looks as follows:
# Change the default $TERM (and alias tmux='tmux -2') set -g default-terminal "screen-256color" # No bells at all set -g bell-action none # Start numbering at 1 set -g base-index 1 # Allows for faster key repetition set -s escape-time 0 # Keep windows around after they exit set -g remain-on-exit off # Change the prefix key to C-a set -g prefix C-a unbind C-b bind C-a send-prefix # Allows us to use C-a a <command> to send commands to a TMUX session inside # another TMUX session bind-key a send-prefix # Rather than constraining window size to the maximum size of any client # connected to the *session*, constrain window size to the maximum size of any # client connected to *that window*.