# Snowflake: Critical incident: Azure - UK South (London): INC0156355

**Summary:** Snowflake reported a critical outage in Azure - UK South (London) from 2026-04-29 03:23 UTC to 2026-04-29 04:44 UTC (1 h 21 min), affecting Snowpark Container Services connectivity, Openflow runtime access and connector data transfers. Restarting unhealthy infrastructure restored service; a postmortem RCA is available on Snowflake Community. _(machine-written, sol)_
- Kind: Major incident · Label: outage (model (Jev))
- Changed: 2026-04-29 03:23 UTC · Detected: 2026-10-17 18:22 UTC
- [Source: https://stspg.io/tn6smjx96fkc](https://stspg.io/tn6smjx96fkc)
- [Company: Snowflake](https://rewindex.com/company/snowflake.md)
- Versions: before (none: first archived) → after incident\_version:164/3g6k24d9ws1k@86b846a2257f
- Change 1 of 1 for this incident

## What changed

**1. Added: Title**

```diff
+ Azure - UK South (London): INC0156355
```

**2. Added: Impact**

```diff
+ critical
```

**3. Added: Status**

```diff
+ postmortem
```

**4. Added: Start time**

```diff
+ 2026-04-29 03:23 UTC
```

**5. Added: Resolved time**

```diff
+ 2026-04-29 04:44 UTC
```

**6. Added: Affected components**

```diff
+ Azure - UK South (London) - Snowpark Container Services, Snowpark Container Services
```

**7. Added: Update** (investigating) · 2026-04-29 03:23 UTC

```diff
+ <b>Current status:</b> We're investigating an issue with Snowflake Data Cloud. We'll provide an update within 30 minutes. <b>Customer experience:</b> Customers hosted in the specified regions may experience errors or connectivity issues when using Snowpark Container Services. Openflow users may be unable to access their runtimes, and Openflow Connectors may fail to pull data from sources or push data to Snowflake. <b>Incident start time:</b> 02:05 UTC April 29, 2026
```

**8. Added: Update** (investigating) · 2026-04-29 03:53 UTC

```diff
+ <b>Current status:</b> We're continuing to investigate the issue with Snowflake Data Cloud. We'll provide another update within 30 minutes. <b>Customer experience:</b> Customers hosted in the specified regions may experience errors or connectivity issues when using Snowpark Container Services. Openflow users may be unable to access their runtimes, and Openflow Connectors may fail to pull data from sources or push data to Snowflake. <b>Incident start time:</b> 02:05 UTC April 29, 2026
```

**9. Added: Update** (monitoring) · 2026-04-29 04:27 UTC

```diff
+ <b>Current status:</b> We've implemented the fix for this issue, and we'll continue to monitor the environment until we're confident all services are functioning properly. <b>Customer experience:</b> Customers hosted in the specified regions may experience errors or connectivity issues when using Snowpark Container Services. Openflow users may be unable to access their runtimes, and Openflow Connectors may fail to pull data from sources or push data to Snowflake. <b>Incident start time:</b> 02:05 UTC April 29, 2026 <b>Incident end time:</b> 04:11 UTC April 29, 2026 <b>Preliminary root cause:</b> A subset of infrastructure that processes DNS requests in the affected region became unhealthy, which caused service connectivity failures for Snowpark Container Services and Openflow.
```

**10. Added: Update** (resolved) · 2026-04-29 04:44 UTC

```diff
+ <b>Current status:</b> We identified a subset of infrastructure that was unhealthy. We restarted that infrastructure and monitored the environment to confirm that the service has been restored. If you experience additional issues or have questions, please open a support case via Snowflake Community or the Support page in Snowsight. <b>Customer experience:</b> Customers hosted in the specified regions may experience errors or connectivity issues when using Snowpark Container Services. Openflow users may be unable to access their runtimes, and Openflow Connectors may fail to pull data from sources or push data to Snowflake. <b>Incident start time:</b> 02:05 UTC April 29, 2026 <b>Incident end time:</b> 04:11 UTC April 29, 2026 <b>Preliminary root cause:</b> A subset of infrastructure that processes DNS requests in the affected region became unhealthy, which caused service connectivity failures for Snowpark Container Services and Openflow. A root cause analysis (RCA) document will be published within five business days.
```

**11. Added: Update** (postmortem) · 2026-05-07 02:26 UTC

```diff
+ Snowflake Engineering has completed the postmortem of this service incident. A detailed Root Cause Analysis \(RCA\) is available on the Snowflake Community site: [https://community.snowflake.com/s/article/INC0156355](https://community.snowflake.com/s/article/INC0156355)
```

## History of this incident

| When (UTC) | Change | Label |
| --- | --- | --- |
| 2026-04-29 03:23 UTC | Critical incident: Azure - UK South (London): INC0156355 (this change) | outage |

All Snowflake changes: [timeline](https://rewindex.com/company/snowflake/changes.md)
_Diff excerpts are shown on normalized text: dates, counters and tokens appear as ‹date›, ‹count›, ‹tok›; noise-only edits are hidden. Rewindex shows the changed passages, not a copy of the page._


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Canonical: https://rewindex.com/change/i7e9d9b77a5ae0e · Markdown: https://rewindex.com/change/i7e9d9b77a5ae0e.md · JSON: https://rewindex.com/api/v1/changes/i7e9d9b77a5ae0e · Generated 2026-10-18T01:54:23.120Z