On PTX1K Series devices, request system reboot is not a supported command even though it is available as part of the Junos OS Command Line Interface (CLI). Running this command will result in the device not being able to recover due to corrupted software.

This article recommends that users use request vmhost reboot instead to reboot the device.

On PTX1K Series devices, running request system reboot will result in the device getting into a bad state and being inaccessible. In fact, the device may not recover from this state even after it is power cycled.

The device is unable to reboot due to bad/corrupted software. 

To come out of this problem, users must perform a USB recovery, which will recover the device in a good state. To perform USB recovery, refer to KB34713 - [MX/PTX] How to perform system reinstall with USB emergency boot media on VMHOST platform [juniper.net] .

The recommendation is that users use request vmhost reboot instead to reboot the device when required.