Claude (Anthropic) outage on September 11, 2026: Elevated errors for Claude Mythos 5.1 and Claude Fable 5.1
Claude reported an incident affecting Claude (Anthropic) for 17 minutes on 11 September 2026, from 14:19 to 14:37 UTC.
Resolved
Official incident reported by Claude
- Started
- 14:19
- 11 Sep 2026 UTC
- Resolved
- 14:37
- 11 Sep 2026 UTC
- Duration
- 17m
- 17 minutes
- Impact
- Major
- as rated by Claude
- Updates
- 5
- posted by Claude
Timeline
All times UTC.
Official incident from Claude
Elevated errors for Claude Mythos 5.1 and Claude Fable 5.1
-
Official
Investigating
We are investigating elevated errors on requests to Claude Fable 5.1 and Claude Mythos 5.1. We will provide an update as soon as possible.
-
Official
Identified
We have identified the cause of elevated errors on requests to Claude Mythos 5.1 and Claude Fable 5.1 and are working on a fix. We will provide an update as soon as possible.
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Official
Monitoring
A fix has been deployed for Claude Mythos 5.1 and Claude Fable 5.1 and we are monitoring for recovery.
-
Official
Monitoring
A fix has been deployed for the issue affecting Claude services and we are monitoring for recovery.
-
Official
Resolved
The issue affecting Claude services has been resolved. Impact occurred from 13:57 to 14:20 UTC
"Official" rows are quoted from Claude's public status page, status.claude.com. Very long posts are shortened.
What our checkpoints saw
HostTracker's checkpoints, which test claude.ai from several locations, recorded no outage of 5 minutes or longer during this incident. A provider can report a problem that affects only some features, regions or accounts, which a check of the main address does not see. The live Claude (Anthropic) status shows what our checks see right now.
Does your product depend on Claude (Anthropic)?
An outage like this one reaches your users through your product, and most teams hear about it from a customer rather than from a dashboard. HostTracker watches any endpoint you name - your own site, an API you call, a vendor you resell - from 300+ locations, confirms a failure from several of them before it says anything, and then tells you by email, SMS, voice call or your chat tool.
You get the same record you are reading here for your own services: every outage timestamped, with the checks that observed it.
Independent measurement by HostTracker. Not affiliated with Claude (Anthropic). Official updates are quoted from Claude's public status page and remain Claude's own words.