This article explains the supported procedure for upgrading an MX240 device from Junos OS 18.2X75-D67.9 to 23.4R2-S5, including pre-upgrade checks, upgrade paths, validation steps, and rollback guidance.
This documentation is applicable for customers planning to upgrade an MX240 router from Junos OS 18.x to Junos OS 23.x.
Basic Pre-Upgrade Checklist :-
Before starting the upgrade, ensure the following:
Confirm hardware compatibility
show chassis hardware
Check current Junos version
show version
Verify storage space
show system storage
Take a configuration backup
save /var/tmp/pre_upgrade_config.conf
Check system alarms and errors
show system alarms
show chassis alarms
Ensure Routing Engine status
show chassis routing-engine
Supported Upgrade Paths:-
Option 1: Multi-Step Upgrade Path (Recommended)
18.2X75-D67.9 → 20.4R3 → 22.4R3 → 23.4R2-S5
This approach follows Juniper-recommended intermediate releases to ensure stability.
Option 2: Reduced-Step Upgrade Path
18.2X75-D67.9 → 20.4R3 → 23.4R2-S5
This path reduces the number of upgrade steps.
Upgrade Procedure:-
Perform the following steps for each upgrade hop:
Copy the Junos image to the device
file copy <image-path> /var/tmp/
Install the Junos image using CLI
request system software add /var/tmp/<image-name> no-validate reboot
Wait for the device to reboot and confirm it comes back online.
Verify the new version
Basic Post-Upgrade Validation:-
After completing the final upgrade to 23.4R2-S5, perform the following checks:
Verify system status
show system uptime
Check Routing Engine and FPC status
show chassis fpc
Verify protocol and interface status
show interfaces terse
show bgp summary
show ospf neighbor
Monitor logs for errors
show log messages
Rollback Procedure :-
If any issues are encountered after the upgrade:
Rollback to the previous Junos version
request system software rollback reboot
Confirm the rollback version
Restore configuration if required
load override /var/tmp/pre_upgrade_config.conf
commit