A condition may occur on SRX devices where a reboot or power cycle initiated from the CLI fails due to insufficient space in the /tmp filesystem. This happens when the tmpfs mount is incorrectly initialized with an abnormally small size.

While attempting to reboot the device using CLI, the following error messages are observed:

request system reboot
Reboot the system ? [yes,no] (no) yes

/usr/libexec/ui/shutdown.sh: cannot create /tmp/rebootcheck.95389: No space left on device
/usr/libexec/ui/shutdown.sh: cannot create /tmp/rebootcheck.95389: No space left on device
awk: can't open file /tmp/rebootcheck.95389
source line number 9
rm: /tmp/rebootcheck.95389: No such file or directory

Additionally, the system storage output shows /tmp at 100% usage with very small capacity:

Filesystem   Size   Used  Avail Capacity Mounted on
tmpfs        152K   152K  0B    100%     /.mount/tmp

The issue is caused by an improperly initialized tmpfs mount for /tmp, resulting in extremely limited space (e.g., ~152 KB).

The problem is isolated to tmpfs mount, perform a physical power cycle of the device to restore the correct tmpfs mounting to resolve the issue.