Verifique as permissões dos diretórios /tmp/tmux*/
. Eles devem ser de sua propriedade e não podem ser acessados por ninguém.
Portanto, altere a permissão como:
chmod 700 -R /tmp/tmux*
It is important that the socket directory is owned by you and not
accessible by everyone, or any user could use your tmux server. For a
while, tmux incorrectly skipped the access mode check, this was fixed
in
2.0.
If your system doesn't support creating directories in /tmp with the
right ownership, you will have to use -S to point it explicitly to a
socket. The check is important and we are not going to support systems
that do not have Unix file permission semantics.