Outage report · Partial outage

Upstash outage on May 11, 2026

Fly.io Upstash Redis service distruption (FRA region)

SeverityPartial outage

StartedMay 11, 2026, 15:05UTC

ResolvedMay 11, 2026, 18:22UTC

Duration3h 17m

What happened

Upstash reported a partial outage starting May 11, 2026, 15:05 UTC. It was marked resolved at May 11, 2026, 18:22 UTC.

The incident lasted 3h 17m from first report to resolution.
It was the 3rd longest of 5 significant outages Upstash reported in the 12 months up to it.
Upstash had reported 1 other partial or major outage in the 90 days before it.
5 other vendors we track reported a significant incident within 12 hours of it.

Latest update from Upstash

On May 12th and 13th at various times, a subset of Upstash Redis instances on [Fly.io](http://Fly.io) experienced intermittent hangs and elevated error rates. The Redis process would stall inside a logging syscall — alive but not making progress — which made the issue hard to spot from our usual telemetry. After investigating with Fly's team, we identified the root cause as a bad interaction between a recent guest kernel update on Fly's newer machines and an upstream Cloud Hypervisor bug \([cloud-hypervisor#7672](https://github.com/cloud-hypervisor/cloud-hypervisor/issues/7672)\) affecting log writes from inside the VM. We mitigated by disabling the affected logging paths, and Fly has since rolled out a hypervisor-side patch, fully resolving the issue. No data was lost. Sorry for the disruption.

Read Upstash's official incident report ↗