Anthropic to Remove Claude Sonnet 4.5 From Claude.ai Chat
Anthropic plans to remove Claude Sonnet 4.5 from Claude.ai Chat, signaling changes to its AI model lineup and user experience strategy.
Jersey City, N.J., May 22, 2026: Anthropic is removing Claude Sonnet 4.5 from the Claude.ai chat interface starting May 26th, 2026, transitioning users to Sonnet 4.6 as the company consolidates infrastructure around newer AI systems with larger context windows and adaptive reasoning capabilities.
According to posts on Reddit’s r/ClaudeAI forum, users are sharing screenshots of the removal notice as the transition appears on Claude.ai. The change is triggering criticism from some writers and long-form users who argue Sonnet 4.5 delivers a stronger conversational tone and creative writing quality than its replacement.
Anthropic introduced Claude Sonnet 4.6 on Feb. 17th, 2026, positioning the model as an upgrade focused on adaptive reasoning, expanded tool use, and a native one-million-token context window.
The removal applies to Anthropic’s consumer-facing chat platform. Reddit users discussing the transition cited Anthropic roadmap documentation showing Sonnet 4.5 support continuing on API platforms through at least Sept. 29, 2026, including through Anthropic API, Amazon Bedrock, and Google Cloud Vertex AI.
Some users on Reddit report preserving older Sonnet 4.5 conversations in hopes those chats remain tied to legacy model versions after the public removal. A community petition shared across discussion forums is also urging Anthropic to preserve Sonnet 4.5 as a permanent legacy option for paid subscribers. Anthropic did not immediately respond to requests for comment about user concerns regarding the transition.
Sonnet 4.6 replaces the manual “extended thinking” structure used in Sonnet 4.5 with adaptive processing that dynamically adjusts reasoning depth based on task complexity. The model also expands enterprise automation and coding-focused workflows.
Developers discussing the migration online reported temporary instability and inconsistent notifications during parts of the rollout, particularly between the Claude.ai web interface and Progressive Web App versions. Anthropic has not publicly commented on infrastructure issues tied to the transition.
The migration is also highlighting a growing divide between benchmark-driven AI improvements and qualitative user preferences. While developers point to stronger coding and reasoning performance in Sonnet 4.6, some creative users describe the newer model as more rigid during storytelling and role-play tasks.
For businesses and marketers, the transition reflects a broader shift in the AI industry as providers move toward continuously updated model ecosystems rather than stable, long-term software versions. The change also highlights growing concerns around workflow continuity, platform dependence, and user trust as AI companies accelerate model replacement cycles.
