This article explains why the boot message WARNING: / was not properly dismounted appears in the output of the command show system boot-messages .

At times, you may see the following message in the output of the command show system boot-messages .

These messages provide a warning during device bootup if the device has an improper/ungraceful (eg. power failed) shutdown in history.

Even after one graceful shutdown process, the messages continue to be seen in the output of the command  show system boot-messages . After upgrading the Junos OS version and rebooting, this message will no longer be seen. This issue can be safely ignored as it is only a warning and will not affect the traffic service.