{"slug": "claude-opus-4-1-retires-august-5-migrate-to-4-8-now", "title": "Claude Opus 4.1 Retires August 5: Migrate to 4.8 Now", "summary": "Anthropic will permanently retire claude-opus-4-1-20250805 on August 5, causing API calls to that model ID to return a 400 error with no fallback. The company recommends migrating to claude-opus-4-8-20260531, which requires updating the model ID and removing temperature, top_p, and top_k parameters, as non-default values now return HTTP 400. Opus 4.8 scores 69.2% on SWE-bench Pro, completes tasks in 15% fewer turns, and generates 35% fewer output tokens compared to 4.7.", "body_md": "On August 5, Anthropic permanently retires `claude-opus-4-1-20250805`\n\n. Requests to that model ID do not degrade or reroute — they return a hard error. The 60-day deprecation window Anthropic announced on June 5 ends Monday. If you haven’t audited your stack yet, you have the weekend.\n\n## What Actually Breaks\n\nAny API call that passes `\"model\": \"claude-opus-4-1-20250805\"`\n\nto Anthropic’s `/v1/messages`\n\nendpoint on or after August 5 gets a 400 response. No silent upgrade. No automatic redirect. No fallback to the next available model. The request fails and your users see an error.\n\nThis is consistent with how Anthropic has handled every prior retirement. When [Sonnet 4 and Opus 4 retired on June 15](https://byteiota.com/claude-sonnet-4-opus-4-retire-june-15-migrate-now/), calls to the old model IDs returned immediate failures with no grace period. Opus 4.1 will be no different.\n\n## Two Things to Fix, Not One\n\nMost migration guides stop at “update your model string.” That’s not enough. There are two distinct breaking changes when moving to the recommended target, `claude-opus-4-8-20260531`\n\n:\n\n**1. The model ID.** Change `claude-opus-4-1-20250805`\n\nto `claude-opus-4-8-20260531`\n\n. The API format, authentication headers, and response structure are identical. Pricing stays at $5/$25 per million input/output tokens. See [Anthropic’s official migration guide](https://platform.claude.com/docs/en/about-claude/models/migration-guide) for the complete model ID reference.\n\n**2. The temperature gotcha.** Starting with Opus 4.7, passing `temperature`\n\n, `top_p`\n\n, or `top_k`\n\nat any non-default value returns HTTP 400. A lot of teams set `temperature=0.7`\n\nto “tune creativity” or `temperature=0`\n\nfor “determinism.” Both values break on 4.8. Remove these parameters entirely. Control output behavior through system prompts instead.\n\n```\n# Before (breaks on August 5 and beyond)\nclient.messages.create(\n    model=\"claude-opus-4-1-20250805\",\n    temperature=0.7,          # HTTP 400 on Opus 4.8\n    max_tokens=1024,\n    messages=[...]\n)\n\n# After\nclient.messages.create(\n    model=\"claude-opus-4-8-20260531\",\n    max_tokens=1024,          # temperature removed\n    messages=[...]\n)\n```\n\n## Where the Old Model ID Hides\n\nMost outages from model deprecations don’t come from the code you’re actively maintaining. They come from the half-archived Lambda function, the LangChain config that hasn’t been touched since last year, or the `.env.staging`\n\nfile nobody remembered updating. Check five places:\n\n**Source code**— direct API call sites and any wrapper abstractions** Config files**— YAML, JSON, TOML configs that store model IDs** Environment variables**—`.env`\n\n,`.env.production`\n\n,`.env.staging`\n\n**CI/CD**— GitHub Actions workflows, Dockerfiles, Jenkins scripts** Framework configs**— LangChain model init params, LlamaIndex LLM configs, LiteLLM proxy settings\n\nRun this before you do anything else:\n\n```\ngrep -r \"opus-4-1\" .   --include=\"*.py\"   --include=\"*.ts\"   --include=\"*.json\"   --include=\"*.yml\"   --include=\"*.env\"\n```\n\nThe short string `opus-4-1`\n\ncatches the model ID across all formats. Don’t search for the full date-stamped string — you’ll miss configs that store it differently.\n\n## What You’re Upgrading To\n\nOpus 4.8 isn’t a patch release. It scores 69.2% on SWE-bench Pro (versus 64.3% for 4.7), completes tasks in 15% fewer turns, and generates 35% fewer output tokens to reach the same result. In practice, it’s about four times less likely to let a code flaw pass without flagging it — which matters if you’re running it in an agentic loop.\n\nIf this forced migration is prompting a larger conversation about model choices, [Claude Opus 5](https://www.anthropic.com/news/claude-opus-5) (released July 24) runs at the same $5/$25 per million token price and roughly doubles Opus 4.8’s performance on Frontier-Bench. Check [Anthropic’s model deprecations page](https://platform.claude.com/docs/en/about-claude/model-deprecations) for the current lifecycle status of every model.\n\n## A Note on Bedrock and Vertex\n\nAmazon Bedrock and Google Vertex AI set their own retirement schedules independently of Anthropic’s direct API. The August 5 hard cutoff applies to calls routed through `api.anthropic.com`\n\n. If your production traffic goes through either cloud provider, check the [Amazon Bedrock model lifecycle page](https://docs.aws.amazon.com/bedrock/latest/userguide/model-card-anthropic-claude-opus-4-1.html) directly — but don’t use that as a reason to delay.\n\nRun the grep now. Fix the model ID. Drop the temperature parameters. Monday is closer than it looks.", "url": "https://wpnews.pro/news/claude-opus-4-1-retires-august-5-migrate-to-4-8-now", "canonical_source": "https://byteiota.com/claude-opus-41-retires-august-5-migrate-to-4-8-now/", "published_at": "2026-08-02 13:11:17+00:00", "updated_at": "2026-08-02 13:23:26.526530+00:00", "lang": "en", "topics": ["artificial-intelligence", "large-language-models", "ai-products", "developer-tools"], "entities": ["Anthropic", "Claude Opus 4.1", "Claude Opus 4.8", "Claude Opus 5", "SWE-bench Pro", "LangChain", "LlamaIndex", "LiteLLM"], "alternates": {"html": "https://wpnews.pro/news/claude-opus-4-1-retires-august-5-migrate-to-4-8-now", "markdown": "https://wpnews.pro/news/claude-opus-4-1-retires-august-5-migrate-to-4-8-now.md", "text": "https://wpnews.pro/news/claude-opus-4-1-retires-august-5-migrate-to-4-8-now.txt", "jsonld": "https://wpnews.pro/news/claude-opus-4-1-retires-august-5-migrate-to-4-8-now.jsonld"}}