tmuxinator で設定した環境が can't find session になって起動しなかったが、tmux kill-server を実行したら同コマンドで tmuxinator を起動させることができた。

ref: https://github.com/tmuxinator/tmuxinator/issues/829#issuecomment-860733135

We were able to fix this issue by restarting the tmux server. Perhaps you upgraded tmux while the previous version was still running?

tmux kill-server