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[SRX] How to upgrade Junos OS on a Chassis Cluster



Article ID: KB17235 KB Last Updated: 07 Feb 2020Version: 21.0

This article explains how to upgrade Junos OS on SRX Chassis Cluster.


  • The SRX device is in a cluster.

  • Junos OS upgrade must be done on both nodes in the Chassis Cluster.



The SRX devices in a Chassis Cluster have the requirement to not have different versions of Junos OS on each node of a cluster. Because of this, we need to ensure that both devices in the cluster come online at the same time. The recommended procedure requires CLI access (either via console, Telnet, or SSH):

  1. Install the software on each cluster member (on node0 and node1) by using the following CLI command (but don't reboot):
request system software add <JUNOS package> no-copy unlink

unlink - (Optional) On J Series Services Routers and SRX devices, this option ensures that the software package is removed at the earliest opportunity in order to make room for the installation to be completed.

Note: Do not reboot until you have executed the above command on each cluster member.

  1. Simultaneouslyenter the following command on each node:
request system reboot

Note: This procedure cannot be performed via J-Web.

Additional helpful High Availability upgrade references:




How to upgrade SRX Chassis Cluster with minimal downtime


[ISSU] Overview and Procedural Steps for In-Service Software Upgrade


ISSU Upgrade limitations on SRX High End Firewalls


What logs to collect when a problem occurs while performing ISSU (In Service Software Upgrade)


How to: Copy a file from one node to the other node in a JSRP Chassis Cluster


SRX Getting Started - Junos Software Installation/Upgrade


Modification History:

2020-02-07: Article reviewed for accuracy. No changes made. Article is correct and complete.


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