Outage in Anthropic

Elevated errors: Invalid `signature` in `thinking` block

Resolved Minor

January 23, 2026 - Started about 7 hours ago - Lasted about 3 hours
Official incident page

Incident Report

The issue has been identified and fix is being implemented.

Components affected

Anthropic api.anthropic.com

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Latest Updates ( sorted recent to last )

RESOLVED about 4 hours ago - at 01/23/2026 07:47AM

This issue is resolved for new requests. However, for responses from one platform received between 2026-01-23 00:00 UTC - 2026-01-23 08:00 UTC that are subsequently included in requests sent to a different platform, there may still be errors.

MONITORING about 4 hours ago - at 01/23/2026 07:32AM

A fix has been implemented and we are monitoring the results.

IDENTIFIED about 6 hours ago - at 01/23/2026 06:24AM

We are continuing to work on a fix for this issue.

IDENTIFIED about 7 hours ago - at 01/23/2026 05:22AM

A mitigation is to _not_ mix Claude API traffic between Bedrock, Vertex, and api.anthropic.com. Each platform is fully operational independently.

IDENTIFIED about 7 hours ago - at 01/23/2026 05:12AM

We are continuing to work on a fix for this issue.

IDENTIFIED about 7 hours ago - at 01/23/2026 05:10AM

We are continuing to work on a fix for this issue.

IDENTIFIED about 7 hours ago - at 01/23/2026 05:09AM

The issue has been identified and fix is being implemented.

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