I am a bit new to tmux and currently I try to setup my config. During that setup I tried to bind C-ö, which loads without errors during the initialization phase of tmux. But in the end the key mapping is not working. I double checked it with other non-umlaut mapping and it works.
The config line looks like that:
bind -r C-ö next-window
I also tried to use different key representations <C-ö>, C-47 and <C-47>. But without luck.
On the other hand when I just map ö there is no problem..
Is it even possible to map umlauts in the combination with Ctrl?
No. Terminals support only a small set of Ctrl keys - @, a-z, [, ], \, ^ and function keys like F1 or Up.
You should be able to bind M-ö instead.