[M/MX/T] Warning message when performing Junos upgrade: ‘js: warning: Modifying reserved identifier junos-xxx is deprecated’

This article explains why warning messages such as ‘js: warning: Modifying reserved identifier junos-xxx is deprecated’ are seen during a Junos OS upgrade. Beginning with 14.1R4, Junos OS displays a warning when a reserved identifier is configured.

During Junos software upgrade process, the following messages are observed:

Junos OS reserves the prefix “junos-” for the identifiers of configurations defined within the junos-defaults configuration group. This means you cannot use “junos-xxx” when defining services/applications. However, the behavior to process this type of configuration is different in various Junos versions:

Before Junos 13.3R1, if you configured user-defined identifiers through the CLI using the reserved prefix, the commit would incorrectly succeed.

From Junos 13.3R1 to 14.1R3, configurations that contain the reserved prefix for user-defined identifiers other than the junos-defaults configuration group identifiers will correctly result in a commit error in the CLI.

Either of these behaviors will block any attempt to upgrade Junos version 13.3R1 or earlier to any later version of Junos OS.

Beginning with 14.1R4, Junos OS will display a warning when a reserved identifier is configured and commit will go through as shown below: