R2 UNC Station Fails to Boot – Error: FATAL: Cannot boot station from sns java.lang.NoClassDefFoundError

[Product_Support]

Issue

A Niagara R2 UNC station fails to start and displays the following error in the Standard Output window:

FATAL: Cannot boot station from sns
java.lang.NoClassDefFoundError: tridium/foundation/prism/Subscription

Product Line

TAC IA Series

Environment

R2 UNC

Cause

This error typically indicates corruption of the operating system or missing Java class definitions required for station boot.

Resolution

To recover the UNC:

1. Reinstall the operating system (OS) on the UNC.
2. Reinstall the Niagara R2 runtime environment (NRE) and required modules.
3. Restore or redeploy the station after the OS and NRE are successfully installed.