# coreService Disruption on USA1226S, USA1228S, USA1230, USA1232

- Provider: [Salesforce](https://down.guide/salesforce)
- Level: confirmed
- Impact: Major outage
- lasted 5h 3m
- started 2026-10-27 20:59 UTC
- coreService
- usa1226s, usa1228s, usa1230, usa1232
- id: DWN-37a26ba1db
- Official page: https://status.salesforce.com/incidents/20004540

## Root cause
> We've determined that the issue is not due to a third-party service disruption.

Category: Upstream dependency. [Postmortem](https://status.salesforce.com/incidents/20004540)

## Updates from Salesforce
### 2026-10-27 21:41 UTC: update
We're aware of an issue impacting multiple Salesforce instances. Since approximately 20:59 UTC, customers on affected instances may have been unable to log in or access their services. We've engaged our third-party partners to assist in the investigation. We'll provide an update in 30 minutes or sooner if additional information becomes available.

### 2026-10-27 22:00 UTC: update
We've determined that the issue is not due to a third-party service disruption. We're now investigating recent changes that may be related, and we're working to find the best path to resolution.

### 2026-10-27 22:10 UTC: update
As a precaution, we've started reverting a recent change to return it to its previous working state, and we're investigating other possible causes.

### 2026-10-27 22:25 UTC: update
We're still reverting the recent change we identified, and we're continuing to investigate other possible causes.

### 2026-10-27 22:46 UTC: update
We're still reverting the recent change, and we're now investigating our network infrastructure.

### 2026-10-27 22:59 UTC: update
We're making progress on rolling back the recent change, and we're also reviewing other recent changes that may be related.

### 2026-10-28 01:09 UTC: update
We have completed a rollback of the recent network configuration change in a lower environment and are working through the remaining validation steps before applying the update to production. 
We'll continue to provide updates as our investigation progresses.

### 2026-10-28 01:38 UTC: impactradiusincrease
Investigations have highlighted that the impact radius is broader than initially understood. We have updated the posting to reflect the additional instances experiencing impact, and customers in these instances will receive communications related to this incident going forward.

### 2026-10-28 02:41 UTC: update
Once we successfully completed the validation steps in the lower environment, and confirmed connectivity was restored. We applied the same fix to the production environment and confirmed customers on affected instances can now log in and access their services. This issue is now resolved.
We apologize for how you and your business may have been affected by this incident. We will thoroughly investigate the incident, confirming the technical trigger, the underlying cause, and preventive action to avoid a repeat in the future.

---
down.guide reads providers' official status pages every minute and adds its own evidence, always labeled. Free, no account. Agents: MCP at https://down.guide/mcp, REST at https://down.guide/api/v1, feeds at https://down.guide/feed. Built by Sazabi (https://sazabi.com/?utm_source=down-guide&utm_medium=markdown).