Anthropic fixes two issues in Claude Opus 4.1, Sonnet 4 and Haiku 3.5

Anthropic has announced that it has fixed two response quality issues in the Claude Opus 4.1, Sonnet 4, and Haiku 3.5 models after user feedback on the response degradation.

“We’ve found and resolved two issues that were affecting quality in some Claude responses. We are continuing to monitor for any ongoing quality issues,” wrote Anthropic.

Earlier, users reported issues such as quality degradation of models, which Anthropic denied, saying that the company never intentionally degrades the performance on increased demand or for other reasons. Instead, it describes this issue as a result of the unknown bugs. Here is the details of the two issues found in Anthropic Claude models.

Resolution of Claude Sonnet 4: Output Quality Degradation

Issue Overview

• A small percentage of Claude Sonnet 4 requests experienced degraded output quality due to a bug from Aug 5-Sep 4, with the impact increasing from Aug 29-Sep 4.

Resolution

• A fix has been rolled out, and this incident has been resolved.

A separate bug affected output quality for some Claude Haiku 3.5 and Claude Sonnet 4 requests from Aug 26-Sep 5. It was fixed with an update.

(source)