Case · 2026-08-18

The family portrait of elevated errors, then just Opus

Start with the whole catalog. End with one model and a tidy UTC range.

Summary: Status page investigated degraded performance across multiple models, listing Mythos 5, Fable 5, Opus 5, Sonnet 5, Haiku 4.5, and others. Later updates narrowed to Opus 5. Official impact window 16:11 to 18:23 UTC. Resolved same day.

Source: status.claude.com · 18 Aug 2026

What landed

On 18 Aug 2026 at 16:20 UTC, status.claude.com investigated degraded performance affecting multiple models, then named Claude Mythos 5, Fable 5, Opus 5, Sonnet 5, Haiku 4.5, and other Claude models.

At 17:12 UTC the update narrowed to elevated errors on Claude Opus 5. Monitoring at 18:26 UTC. Resolved at 19:01 UTC with impact on Opus 5 from 16:11 to 18:23 UTC.

Surfaces: claude.ai, Claude API, Claude Code, Claude Cowork.

Why it matters

The first note is a roll call. The last note is a two-hour Opus window. Users on the other names in the first update do not get a separate receipt.

Satire margin

Everyone was invited. Opus stayed for coffee. The minutes still list the whole family.

Primary source

Status: degraded performance for multiple models (18 Aug)

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