Postmortem

On September 4, 2026, OpenAI (ChatGPT and Codex), Anthropic (Claude), Google (Gemini), and xAI (Grok) all suffered degraded service within the same few hours — a simultaneous, multi-model outage that left companies with four redundant “independent” providers and zero working fallbacks at once. The root cause was not single-vendor failure but correlated infrastructure: shared cloud regions, shared network paths, and a shared accelerator supply chain. This guide breaks down what actually happened, the recurring postmortem fingerprints to recognize, and how to build a failover design that survives this class of correlated outage — including the documented non-AI path every organization needs before the next 3-hour window arrives. ...

On August 17, 2026, GitHub suffered a 7-hour-and-47-minute outage that took down Issues, Pull Requests, the API, Actions, and Copilot, with peak web and API error rates around 20% and archive downloads failing roughly half the time. The root cause was a single misconfigured autoscaling policy on an Istio sidecar that cascaded through load balancers, the authentication path, and client retry logic into a platform-wide failure. This postmortem breaks down exactly what happened, why retry storms amplified the damage tenfold, and what the incident teaches operators about building reliable systems in the age of AI agents. ...