Unable to open tmux on Ubuntu: "error creating /tmp/tmux-5172 (Permission denied) [closed]

I am having trouble opening tmux on my Ubuntu system. Every time I try to start tmux, I receive the following error message:

tmux> error creating /tmp/tmux-5172 (Permission denied)

Here are the steps I have taken so far:

Tried changing the permissions of /tmp to 777:

sudo chmod -R 777 /tmp

Verified the ownership of /tmp:

sudo chown root:root /tmp

Checked the permissions of /tmp:

ls -ld /tmp> drwxrwxrwt 238 root root 16384 Aug  7 08:50 /tmp/

Checked disk space in /tmp:

df -h /tmp> Filesystem      Size  Used Avail Use% Mounted on> /dev/vda3       1.6T  702G  810G  47% /