I got the same issue. "systemctl status systemd-tmpfiles-setupd-dev.service" yields the same response. But my system (Ubunutu 18.04.1) is starting properly and there are no problems when using it.
In /var/log/syslog these lines precede the error:
Jan 11 14:37:48 Intel-i5-Tower systemd[1]: Started Apply Kernel Variables.
Jan 11 14:37:48 Intel-i5-Tower systemd-tmpfiles[311]: Unsafe symlinks encountered in /dev/cuse, refusing.
Jan 11 14:37:48 Intel-i5-Tower systemd-tmpfiles[311]: Unsafe symlinks encountered in /dev/autofs, refusing.
Jan 11 14:37:48 Intel-i5-Tower systemd-tmpfiles[311]: Unsafe symlinks encountered in /dev/btrfs-control, refusing.
Jan 11 14:37:48 Intel-i5-Tower systemd-tmpfiles[311]: Unsafe symlinks encountered in /dev/userio, refusing.
Jan 11 14:37:48 Intel-i5-Tower systemd-tmpfiles[311]: Unsafe symlinks encountered in /dev/vfio, refusing.
Jan 11 14:37:48 Intel-i5-Tower systemd-tmpfiles[311]: Unsafe symlinks encountered in /dev/vfio/vfio, refusing.
Jan 11 14:37:48 Intel-i5-Tower systemd-tmpfiles[311]: Unsafe symlinks encountered in /dev/vhci, refusing.
Jan 11 14:37:48 Intel-i5-Tower systemd-tmpfiles[311]: Unsafe symlinks encountered in /dev/uhid, refusing.
Jan 11 14:37:48 Intel-i5-Tower systemd-tmpfiles[311]: Unsafe symlinks encountered in /dev/vhost-net, refusing.
Jan 11 14:37:48 Intel-i5-Tower systemd-tmpfiles[311]: Unsafe symlinks encountered in /dev/vhost-vsock, refusing.
Jan 11 14:37:48 Intel-i5-Tower systemd-tmpfiles[311]: Unsafe symlinks encountered in /dev/snd, refusing.
Jan 11 14:37:48 Intel-i5-Tower systemd-tmpfiles[311]: Unsafe symlinks encountered in /dev/snd, refusing.
Jan 11 14:37:48 Intel-i5-Tower systemd-tmpfiles[311]: Unsafe symlinks encountered in /dev/snd/timer, refusing.
Jan 11 14:37:48 Intel-i5-Tower systemd-tmpfiles[311]: Unsafe symlinks encountered in /dev/snd/seq, refusing.
Jan 11 14:37:48 Intel-i5-Tower systemd[1]: systemd-tmpfiles-setup-dev.service: Main process exited, code=exited, status=1/FAILURE
Jan 11 14:37:48 Intel-i5-Tower systemd[1]: systemd-tmpfiles-setup-dev.service: Failed with result 'exit-code'.
Jan 11 14:37:48 Intel-i5-Tower systemd-fsck[584]: Ubuntu/home: sauber, 316299/66273280 Dateien, 223989723/265086556 Blöcke
Jan 11 14:37:48 Intel-i5-Tower systemd[1]: Failed to start Create Static Device Nodes in /dev.
Jan 11 14:37:48 Intel-i5-Tower systemd[1]: Reached target Local File Systems (Pre).
I got the same issue. "systemctl status systemd- tmpfiles- setupd- dev.service" yields the same response. But my system (Ubunutu 18.04.1) is starting properly and there are no problems when using it. tmpfiles[ 311]: Unsafe symlinks encountered in /dev/cuse, refusing. tmpfiles[ 311]: Unsafe symlinks encountered in /dev/autofs, refusing. tmpfiles[ 311]: Unsafe symlinks encountered in /dev/btrfs-control, refusing. tmpfiles[ 311]: Unsafe symlinks encountered in /dev/userio, refusing. tmpfiles[ 311]: Unsafe symlinks encountered in /dev/vfio, refusing. tmpfiles[ 311]: Unsafe symlinks encountered in /dev/vfio/vfio, refusing. tmpfiles[ 311]: Unsafe symlinks encountered in /dev/vhci, refusing. tmpfiles[ 311]: Unsafe symlinks encountered in /dev/uhid, refusing. tmpfiles[ 311]: Unsafe symlinks encountered in /dev/vhost-net, refusing. tmpfiles[ 311]: Unsafe symlinks encountered in /dev/vhost-vsock, refusing. tmpfiles[ 311]: Unsafe symlinks encountered in /dev/snd, refusing. tmpfiles[ 311]: Unsafe symlinks encountered in /dev/snd, refusing. tmpfiles[ 311]: Unsafe symlinks encountered in /dev/snd/timer, refusing. tmpfiles[ 311]: Unsafe symlinks encountered in /dev/snd/seq, refusing. tmpfiles- setup-dev. service: Main process exited, code=exited, status=1/FAILURE tmpfiles- setup-dev. service: Failed with result 'exit-code'.
In /var/log/syslog these lines precede the error:
Jan 11 14:37:48 Intel-i5-Tower systemd[1]: Started Apply Kernel Variables.
Jan 11 14:37:48 Intel-i5-Tower systemd-
Jan 11 14:37:48 Intel-i5-Tower systemd-
Jan 11 14:37:48 Intel-i5-Tower systemd-
Jan 11 14:37:48 Intel-i5-Tower systemd-
Jan 11 14:37:48 Intel-i5-Tower systemd-
Jan 11 14:37:48 Intel-i5-Tower systemd-
Jan 11 14:37:48 Intel-i5-Tower systemd-
Jan 11 14:37:48 Intel-i5-Tower systemd-
Jan 11 14:37:48 Intel-i5-Tower systemd-
Jan 11 14:37:48 Intel-i5-Tower systemd-
Jan 11 14:37:48 Intel-i5-Tower systemd-
Jan 11 14:37:48 Intel-i5-Tower systemd-
Jan 11 14:37:48 Intel-i5-Tower systemd-
Jan 11 14:37:48 Intel-i5-Tower systemd-
Jan 11 14:37:48 Intel-i5-Tower systemd[1]: systemd-
Jan 11 14:37:48 Intel-i5-Tower systemd[1]: systemd-
Jan 11 14:37:48 Intel-i5-Tower systemd-fsck[584]: Ubuntu/home: sauber, 316299/66273280 Dateien, 223989723/265086556 Blöcke
Jan 11 14:37:48 Intel-i5-Tower systemd[1]: Failed to start Create Static Device Nodes in /dev.
Jan 11 14:37:48 Intel-i5-Tower systemd[1]: Reached target Local File Systems (Pre).
Perhaps the error is due to the unsave symlinks?