ubuntu server poweroff and reboot and others can not work in terminal [closed]-Collection of common programming errors

Ubuntu server can not reboot or poweroff. And other commands can not run!

root@cloud1:~# reboot
Sorry, command-not-found has crashed! Please file a bug report at:
https://bugs.launchpad.net/command-not-found/+filebug
Please include the following information with the report:

command-not-found version: 0.2.44
root@cloud1:~# lsof -i:8080
Sorry, command-not-found has crashed! Please file a bug report at:
https://bugs.launchpad.net/command-not-found/+filebug
Please include the following information with the report:

command-not-found version: 0.2.44