Microsoft Azure Central US outage
Microsoft 365 services including Teams, OneDrive and Defender, along with other Azure-dependent services, went down for roughly 14 hours in Microsoft's Central US region, disrupting businesses worldwide — coincidentally just hours before the unrelated CrowdStrike outage hit many of the same customers.
The damage was public. The root cause was preventable.
Microsoft 365 services including Teams, OneDrive and Defender, along with other Azure-dependent services, went down for roughly 14 hours in Microsoft's Central US region, disrupting businesses worldwide — coincidentally just hours before the unrelated CrowdStrike outage hit many of the same customers.
What the software actually got wrong
Microsoft found that a backend cluster-management workflow deployed a configuration change that blocked connectivity between a subset of Azure Storage clusters and their compute resources, causing affected virtual machines to lose access to their virtual disks and automatically reboot, which then cascaded into every service built on top of those resources.
Microsoft found that a backend cluster-management workflow deployed a...
Microsoft found that a backend cluster-management workflow deployed a configuration change that blocked connectivity between a subset of Azure Storage clusters and their compute resources, causing affected virtual machines to lose access to their virtual disks and automatically reboot, which then cascaded into every service built on top of those resources.
Requs AI Edge Case flags this exact pattern at the requirements and architecture stage — before a single line of code implementing it exists — so the assumption behind it gets challenged while it is still cheap to fix.
Beyond code coverage and "shall" testing
Root causes like this one rarely show up in code coverage or requirements-compliance testing, because nobody wrote a requirement anticipating the specific edge case that broke. Requs AI Edge Case and Requs AI Software FMEA are built to surface exactly this class of overlooked failure mode — before the software is written.
Surfaces this before code exists
Identifies edge cases like this one at requirements and architecture time, using the Common Defect Enumeration to catalog failure patterns seen across hundreds of real-world software failures — including this one.
Connects the failure mode to the hazard
Traces this class of root cause directly to the system-level hazard it can produce, so a defect pattern like this one gets flagged during design review instead of after it ships.
Find the overlooked root causes before they ship.
Schedule a demonstration, or explore how Requs AI Edge Case and Software FMEA use the Common Defect Enumeration.