← Back to the 309 Software Failures Timeline
Case Study #309 — 309 Software Failure Events Timeline

Cloudflare global network outage

A roughly five-hour outage at Cloudflare, which sits in front of about a fifth of all websites, broke access to a huge swath of the internet at once, including ChatGPT, X, Spotify, Canva and Discord, with estimated losses in the hundreds of millions of dollars.

2025-11-18
When it happened
Technology
Sector
#309 of 309
Ranked by documented impact
01 — What Happened

The damage was public. The root cause was preventable.

A roughly five-hour outage at Cloudflare, which sits in front of about a fifth of all websites, broke access to a huge swath of the internet at once, including ChatGPT, X, Spotify, Canva and Discord, with estimated losses in the hundreds of millions of dollars.

Technology
Sector affected
2025-11-18
Date of the event
#309
Rank in the 309 Software Failure Events Timeline
3
Distinct root-cause clauses identified below
02 — The Root Cause

What the software actually got wrong

Cloudflare's own postmortem found that a routine change to database permissions caused an internal query to return duplicate rows, doubling the size of a 'feature file' used by its bot-detection system; that oversized file was then automatically distributed to Cloudflare's entire global network, and the traffic-routing software on every server had a hard-coded size limit below the file's new size, causing the routing software itself to crash worldwide.

01Root Cause

Cloudflare's own postmortem found that a routine change to...

What Happened

Cloudflare's own postmortem found that a routine change to database permissions caused an internal query to return duplicate rows, doubling the size of a 'feature file' used by its bot-detection system

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.

02Root Cause

That oversized file was then automatically distributed to Cloudflare's...

What Happened

that oversized file was then automatically distributed to Cloudflare's entire global network

How Requs AI Catches This

Requs AI Software FMEA traces this failure mode back to the system-level hazard it feeds, tagging it against the Common Defect Enumeration so it surfaces in review instead of in the field.

03Root Cause

The traffic-routing software on every server had a hard-coded...

What Happened

the traffic-routing software on every server had a hard-coded size limit below the file's new size, causing the routing software itself to crash worldwide

How Requs AI Catches This

Requs AI Edge Case and Software FMEA together treat this as a known, catalogued defect pattern — not a novel surprise — so it gets tested for deliberately rather than discovered after deployment.

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.