# Upstash: Fly.io Upstash Redis service distruption (FRA region)

- Impact (vendor’s label): major
- Status: postmortem
- Started: 2026-05-11 15:05 UTC · Resolved: 2026-05-11 18:22 UTC · Duration: 3.3 h
- Updates: 5
- [Vendor status page: https://stspg.io/xc9fkbk20d2w](https://stspg.io/xc9fkbk20d2w)
- [Company: Upstash](https://rewindex.com/company/upstash.md)

## Summary

Upstash reported a major degradation affecting some Fly.io Redis databases in FRA, with increased latency or timeouts. It started at 2026-05-11 15:05 UTC and resolved at 2026-05-11 18:22 UTC, lasting 3 h 16 min. The postmortem described Redis processes stalling inside a logging syscall; the supplied root-cause explanation is truncated. _(machine-written, sol)_
## Timeline of updates

- **investigating** 2026-05-11 15:05 UTC: Some databases may experience increased latency or timeouts in Fly.io’s FRA region.
- **investigating** 2026-05-11 15:07 UTC: We are continuing to investigate the issue.
- **investigating** 2026-05-11 17:19 UTC: We are working with Fly team to investigate the root cause.
- **resolved** 2026-05-11 18:22 UTC: The incident has been resolved. We are working with Fly team on RCA.
- **postmortem** 2026-05-15 12:49 UTC: 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.

## Rewindex changes for this incident

- 2026-05-11 15:05 UTC: [Major incident: Fly.io Upstash Redis service distruption (FRA region)](https://rewindex.com/change/if87001a23cf3c8.md)


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Canonical: https://rewindex.com/company/upstash/incidents/47bg91tdj0hz · Markdown: https://rewindex.com/company/upstash/incidents/47bg91tdj0hz.md · JSON: https://rewindex.com/api/v1/companies/upstash/incidents/47bg91tdj0hz · Generated 2026-10-18T09:54:07.993Z