I spent several hours trying to get to the bottom of why tmux was crashing as soon as I ran it on Fedora. It turns out there’s a simple fix. When tmux starts it uses /dev/ptmx to create a new TTY (virtual terminal) that the user can interact with. If your user does not have permission to access this device then tmux will silently die. A good way to verify this is to try running screen too.

In my case I realised that my user was not a member of the user group “tty” on my system. The answer was therefore simple:

sudo usermod -a -G tty james

I hope this helps someone avoid spending hours searching for the right incantation.