Sonnet 4.6 and Opus 4.6 both saw elevated errors on April 4, 2026
This was a useful historical marker because it was not limited to one model family. Two major model lines experienced elevated error rates at the same time.
Published: Apr 4, 2026, 1:09 PM EDT
Updated: Apr 21, 2026, 8:40 AM EDT
Incident started: Apr 4, 2026, 1:09 PM EDT
Crowd spike noticed: Apr 4, 2026, 1:14 PM EDT
Resolved: Apr 4, 2026, 1:30 PM EDT
Affected surface: Claude Sonnet 4.6 and Claude Opus 4.6 across most product surfaces
Official updates said Sonnet 4.6 and Opus 4.6 experienced elevated error rates across most product surfaces before the incident resolved.
- Unlike narrower model incidents, this one hit two major model families together.
- The official language suggested the impact reached across most product surfaces, even though the failure still looked model-centered.
- This makes it a stronger historical signal than a one-model blip.
A reviewed note on the April 4, 2026 multi-model incident affecting both Sonnet 4.6 and Opus 4.6 across most product surfaces.
Review the methodology page for how crowd reports are deduplicated and the status lag explainer for how independent reports differ from provider updates.
If you want the broader archive context, go back to the Claude outage history page.
Related notes in the same incident category: