julian@julian-ThinkPad-E550:~$ sudo reboot
[sudo] password for julian: 
Failed to start reboot.target: Transaction is destructive.
See system logs and 'systemctl status reboot.target' for details.
julian@julian-ThinkPad-E550:~$ systemctl status reboot.target
● reboot.target - Reboot
   Loaded: loaded (/lib/systemd/system/reboot.target; disabled; vendor preset: d
   Active: inactive (dead)
     Docs: man:systemd.special(7)
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