Major incident

Cornerstone: vILT Integrations Error in UK PRD & PIL

Affected: Response Time, Response Time, Response Time, Response Time

Current status of Cornerstone: Operational — live Cornerstone status

Timeline

1. Aug 20, 2026, 12:06 UTC
   identified
   Error when creating vILT session (Microsoft Teams VILT Integration): "Error while creating Schedule: Exception of type 'System.ArgumentException' was thrown." Cause has been found and we are working on the fix.
2. Aug 20, 2026, 12:51 UTC
   resolved
   This incident has been resolved.
3. Sep 1, 2026, 06:47 UTC
   postmortem
   **Root Cause Analysis** ‌ **Incident Summary:** On August 20th, 2026, users in the UK Production and Pilot environments, across all swimlanes, experienced issues creating VILT sessions. **Impact:** Users were unable to create VILT sessions, resulting in temporary disruption to VILT-related functionality. **Root Cause:** The issue was related to the availability of the required messaging queues used by the VILT integration service. The queues were not available as expected, resulting in exceptions and preventing the service from processing VILT requests successfully. **Resolution:** The VILT integration service was redeployed in the UK Production and Pilot environments. Following the redeployment, the required queues were successfully established and the exceptions stopped. VILT session creation functionality was restored. **Preventive Measures:** * Queue availability and service startup dependencies are being reviewed to ensure the required queues are available during service initialization * Startup and redeployment sequencing are being reviewed to prevent similar queue initialization issues in the future

Updates as published by Cornerstone (original).