After a power outage a device came back online and reflected a new commit comment "Junos has activated Recovery Mode" without any human intervention:

root@SW> show system commit
...
11 2025-03-16 14:21:17 UTC by root via other
   Junos has activated Recovery Mode
...

The device also came back online with a default configuration. As a result it impacted the hosts traffic as the ports were no longer assigned specific port-profiles from Mist.

The message "Junos has activated Recovery Mode" indicates the EX3400 switch booted into Recovery Mode after the power outage. This typically happens when:

- The filesystem is corrupted (due to improper shutdown).

- The primary Junos configuration (/config/juniper.conf) is missing or damaged.

- The system couldn't mount the necessary partitions during boot.

So Junos loaded a default factory-like configuration to allow basic recovery, reverting any custom port profiles to the system default profiles in the process. Junos allows saving a "rescue configuration" as a fallback, but if none was saved, the system defaults to Recovery Mode.

To prevent this issue:

1 - Make sure to have a redundant UPS, to prevent ungraceful shutdowns.

2 - Save a known-good config as a rescue backup:

> request system configuration rescue save

Verify it with:

> show system configuration rescue

Note: Rescue config should be updated periodically to keep it as current as possible.

2025-05-21 : Article Created

2026-05-27 : Added hyperlink in related info

Techpub Document: Rescue and Recovery of Configuration File (Junos OS)