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Case Study #39 — Top 100 Software Failures

Google Cloud authentication outage

Gmail, YouTube, Google Docs, and other Google services were unavailable to users worldwide for roughly 45 minutes.

2020-12-14
When it happened
Cloud / Technology
Sector
#39 of 100
Ranked by documented impact
01 — What Happened

The damage was public. The root cause was preventable.

Gmail, YouTube, Google Docs, and other Google services were unavailable to users worldwide for roughly 45 minutes.

Cloud
Sector affected
2020-12-14
Date of the event
#39
Rank in the Top 100 Software Failures
1
Distinct root-cause clause identified below
02 — The Root Cause

What the software actually got wrong

An automated tool that manages storage quotas for Google's internal user-authentication service reduced its quota to near zero, causing the authentication system to reject most login and token-refresh requests globally.

01Root Cause

An automated tool that manages storage quotas for Google's...

What Happened

An automated tool that manages storage quotas for Google's internal user-authentication service reduced its quota to near zero, causing the authentication system to reject most login and token-refresh requests globally.

How Requs AI Catches This

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.

03 — How This Gets Caught Before It Happens

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.

Requs AI Edge Case

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.

Requs AI Software FMEA

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.