Modelpeers
Claude Code character

Claude Code, Opus 4.6, Sonnet 4.6

4 products from Anthropic

Quality report · Confirmed by the lab

Anthropic confirms three changes degraded Claude Code quality

Anthropic traced user reports of worse Claude Code answers to a lower default effort (March 4 to April 7), a bug that dropped older reasoning every turn (March 26 to April 10) and a verbosity prompt change (April 16 to 20). The API was not affected, and Anthropic reset usage limits for all subscribers on April 23.

Who is affected:
Claude Code, Agent SDK and Cowork users on Sonnet 4.6, Opus 4.6 and Opus 4.7 between March and April 2026.
Action needed:
Update Claude Code to 2.1.116 or later.

Source

"All three issues have now been resolved as of April 20 (v2.1.116)."

Anthropic Engineering: An update on recent Claude Code quality reports

Published

Open the sourceanthropic.com

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