tmux: open terminal failed: missing or unsuitable terminal: xterm-256color

Question

Your system doesn’t have xterm-256color. You could:

Set TERM to something other than xterm-256color outside tmux (try just plain export TERM=xterm).
See if there is a package containing xterm-256color, perhaps a later version of ncurses or terminfo.
Install it manually from another system with something like:
```
infocmp -x xterm-256color > out
```
Then transfer the “out” file to your Mac and try:
```
tic out
```