Sierra ; Polaris DC04 - RCA - April 11, 2026

Introduction

This document serves as a Root Cause Analysis for the service interruption experienced by Sierra and Polaris customers–hosted in DC04 (Chicago Data Center).

The goal of this document is to share our findings regarding the event, specify the root cause analysis, outline actions to be taken to solve the downtime event, as well as preventive measures Clarivate is taking to avoid similar cases in future.

Event Timeline

Service interruption was experienced by the single-tenant Sierra and Polaris environments hosted in Clarivate’s Data center in Chicago, during the following days:

April 11, 2026, from 12:14 AM until 2:27 AM CDT.

During the event, the service was inaccessible.

Root Cause Analysis

Clarivate Engineers investigated this event to determine the root cause analysis with the following results:

On April 11, all products hosted on DC04 experienced an interruption triggered by planned maintenance from our primary Internet Service Provider. Our systems are built with redundancy to automatically failover to a secondary provider; however, the primary ISP's maintenance protocol kept their foundational network routing signals (BGP session and default route) continuously active despite the underlying loss of connectivity. Because these routing signals never dropped, our network was unable to detect the link as down, which prevented the automatic failover from triggering as designed. To restore service, our network engineering team and on-site data center partners manually disconnected the primary link, successfully forcing all traffic to route through our fully operational secondary ISP.

Technical Action Items and Preventive Measures

Clarivate has taken the following actions and preventive measures to avoid such an occurrence in future:

· The network team working to enhance our ISP failover mechanism to include more checks in order to determine if the line is down and trigger the failover accordingly.

Customer Communication

Innovative is committed to providing customers with prompt and ongoing updates during Cloud events. Ongoing and prompt updates on service interruptions appear in the system status portal at this address:http://status.exlibrisgroup.com/

These updates are automatically sent as emails to registered customers