Unable to write to /tmp directory in macOS, unable to correct permissions: “Operation not permitted”

Solution 1:

  1. Reboot your Mac into recovery mode
  2. Open Utilities menu in the top bar > open Terminal

    csrutil disable
    
  3. Reboot

  4. Remove the tmp folder

    sudo rm -i /tmp
    sudo rm -i /private/tmp
    
  5. Create tmp folder

    sudo mkdir /private/tmp
    sudo chown root:wheel /private/tmp
    sudo chmod 1777 /private/tmp
    
  6. Create the symlink

    sudo ln -s /private/tmp /tmp
    
  7. Run repair_packages (you may not need to do this)

    sudo /usr/libexec/repair_packages --repair --standard-pkgs --volume /
    
  8. Reboot back to recovery mode and run

    csrutil enable
    
  9. Reboot


Props to Andrew Ferk for figuring out a fix; pulling out your comment as a community wiki answer so it's more readable.

Solution 2:

sudo chmod 1777 /private/tmp

Did it for me.