This document provide an overview of the use and implications of the option "no-validate" during Junos upgrade.

During to upgrade of Junos version, we have the option to add "no-validate". What are the implications when this is used and when not?

The default is the validation. This means the configuration will be validated when nothing is specified for it. When you use the validate knob the device will validate if the existing configuration is compatible with the new image before the actual upgrade or downgrade starts and let you know what is the issue and stop the upgrade if any incompatibilities were found. Using the no-validate the upgrade will succeed but if there are configuration compatibility discrepancies between the old image and new image, the system may not be able to apply the configuration when the system comes up on a newer software image after the upgrade and traffic may get impacted until the configuration is corrected and manually committed. In other words, the no-validate' option will bypass most sanity checks, so MUST be used with caution.

2024-4-19: updated Categories to include MX-Series, EX-series, and QFX-series.