# Fly.io Upstash Redis Service Distruption

- Provider: [Upstash](https://down.guide/providers/upstash)
- Confidence: Confirmed
- Impact: Major outage
- lasted 3h 59m
- started 2026-05-12 09:49 UTC
- id: DWN-8f8a7692dd
- Official page: https://stspg.io/v8n17s5pgq0y

## Updates from Upstash
### 2026-05-12 09:49 UTC: investigating
Some regions are experiencing connectivity issues due to an ongoing network problem. We are currently investigating

### 2026-05-12 10:50 UTC: identified
The issue has been identified and the fix is being implemented.

### 2026-05-12 12:05 UTC: monitoring
A fix has been implemented and we are monitoring the results.

### 2026-05-12 13:48 UTC: resolved
This incident has been resolved.

### 2026-05-15 12:43 UTC: postmortem
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.

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