Incident Summary
On July 13, 2026, customers using Microsoft (Office 365) for email and calendar integration experienced service disruptions. Affected users were unable to authorize or re-authorize their email and calendar connections within Lever, often encountering an "Unknown error" message. Additionally, outbound emails sent through the Microsoft integration failed to deliver during this period. Google-based email and calendar services remained fully operational and were not impacted by this incident.
Detection
The issue was identified on July 13, 2026, at 2:22 PM ET, following reports from customers to our Support team. Upon investigation, the engineering team confirmed the failures and initiated a high-priority response. While the underlying technical expiration occurred on July 12, 2026, the impact became visible as users attempted to refresh permissions or send outbound communications the following day.
Root Cause
The incident was caused by the expiration of a digital security credential used to securely communicate with Microsoft. This credential acts as a secure "password" that allows our systems to sync email and calendar data. Because this was a shared credential used for the Microsoft integration, the expiration affected customers using Office 365 broadly rather than a specific account.
Resolution
To resolve the issue, our engineering team generated a new security credential and updated the integration settings across our environments. Once the new credential propagated through the system, service was fully restored. Restoration was verified through internal testing and confirmed by successful customer re-authorizations by 8:28 PM ET on July 13, 2026. No data loss occurred as a result of this incident.
Preventative Measures
To prevent a recurrence of this issue, we are implementing the following improvements: