Introduction

This document serves as a Root Cause Analysis for the Summon service interruption experienced by Clarivate customers on July 7, 2026.

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.

Affected Products

Summon / CDI

Event Timeline

Service interruption was experienced by the CDI and Summon Search services on:

July 7, 2026, from 06:32 UTC until 08:10 UTC.

During the event, the service was intermittently unavailable or slow to respond for end users.

Root Cause Analysis

Clarivate engineers investigated this event with the following results:

On the morning of July 7, the CDI and Summon Search services experienced a period of instability caused by an unusual increase in incoming queries requesting very large result sets. This traffic pattern placed heavy load on the underlying search cluster, which slowed responses and caused several Search API servers to run out of memory and crash.

Further analysis confirmed that the unusually high request volume originated from Primo VE. The development team identified this behavior as the source of the increased load on the CDI and Summon Search services and proceeded with a corrective change in Primo VE to stop the excessive request pattern.

Because of the way traffic was redistributed when servers became unhealthy, the additional load shifted onto the remaining servers, leading them to fail in succession across data centers. Initial restarts brought the service back only briefly, as the same pressure quickly destabilized the environment again.

Service was fully restored after a coordinated, simultaneous restart of the affected servers across all data centers, which returned them to healthy status behind the load balancers and resumed normal operation worldwide.

Technical Action Items and Preventive Measures 

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

• Corrective action was taken in Primo VE to address the excessive request pattern that contributed to the service instability. The development team deployed the fix to as a code injection on July 8, 2026.

• We are reviewing how traffic is balanced across our servers and data centers, and how the system responds when one component is under stress. The goal is to ensure that a localized slowdown remains contained and does not affect the wider service, keeping Summon and CDI resilient and available for our customers worldwide.

• Customer Communication

Clarivate 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.