Anthropic is retiring Claude Opus 4.1 on August 5, 2026 — here's what developers need to do
Anthropic has deprecated claude-opus-4-1-20250805 with a retirement date of August 5, 2026. Opus 4.8 is the recommended replacement.
On June 5, Anthropic notified API developers that Claude Opus 4.1 (claude-opus-4-1-20250805) is now deprecated, with a firm retirement date of August 5, 2026. From that date, any requests to that model ID will fail. The recommended replacement is Claude Opus 4.8.
This applies to the Claude API, Claude Platform on AWS, and Microsoft Foundry. If you’re using this model through Amazon Bedrock or Vertex AI, those platforms set their own retirement schedules, so check with them directly.
What “deprecated” actually means
Anthropic uses four stages to describe a model’s lifecycle: Active, Legacy, Deprecated, and Retired.
Deprecated sits between legacy and gone. The model still works today, but Anthropic no longer recommends it, has assigned a retirement date, and will stop serving it entirely once that date arrives. You have roughly two months from the June 5 notification to migrate before things start breaking.
Anthropic’s policy is to give at least 60 days notice before retiring any publicly released model, so August 5 sits right at that minimum window. There’s no buffer built in beyond what they’ve already given you.
Why this is happening now
The Opus line has moved quickly. Claude Opus 4.1 launched in August 2025, and since then Anthropic has shipped Opus 4.5, 4.6, 4.7, and now 4.8. That’s a lot of model versions in a short span, and Anthropic has been explicit that it retires older models to free up capacity for newer ones.
Opus 4 (claude-opus-4-20250514) and Sonnet 4 (claude-sonnet-4-20250514) are also being retired, with a closer deadline of June 15, 2026. If you have any of those in production, those should be your first priority.
What Opus 4.8 brings to the table
Claude Opus 4.8 is Anthropic’s current most capable generally available model, and it’s a meaningful step up from 4.1 in a few specific ways.
The headline improvement is judgment. In agentic and coding contexts, Opus 4.8 is notably better at catching its own mistakes before they propagate, asking clarifying questions at the right moments, and pushing back on plans that don’t hold up. Anthropic’s own evaluations found it roughly four times less likely to leave flaws in its own code unremarked compared to its predecessor. If you’re using Opus in any kind of autonomous or multi-step workflow, that matters.
On context, Opus 4.8 supports a 1 million token context window on the Claude API, Amazon Bedrock, and Vertex AI. Microsoft Foundry gets 200k. Max output is 128k tokens.
Pricing starts at $5 per million input tokens and $25 per million output tokens. Prompt caching can reduce that by up to 90%, and batch processing by 50%. One small but useful detail: the minimum prompt length to qualify for caching is 1,024 tokens, lower than on Opus 4.7. Prompts that were previously too short to cache may now benefit without any code changes on your part.
What you need to do
If you’re hardcoding model IDs in your applications, this is the task: find every reference to claude-opus-4-1-20250805 and update it to claude-opus-4-8.
A few practical steps worth following:
Audit your usage now. Anthropic provides an API usage audit tool in the platform to help you locate deprecated model calls across your applications. Use it before you assume you’ve caught everything.
Test before the deadline. Don’t swap model IDs on August 4. Give yourself time to test prompts, check output quality, and validate that your application behaves as expected with Opus 4.8. The models are not identical, and depending on your use case, you may need to adjust prompts.
Note the model ID format. Opus 4.8’s ID is claude-opus-4-8 without a date suffix. Starting with the 4.6 generation, Anthropic moved to dateless model IDs that are still pinned snapshots, not evergreen pointers. You’re not getting automatic updates by using the shorter format.
Check your partner platforms separately. If any part of your stack runs through Bedrock or Vertex AI, the August 5 date doesn’t automatically apply. Those platforms will publish their own timelines.
If you don’t act
Requests to claude-opus-4-1-20250805 after August 5, 2026 will return errors. That’s not a soft failure or a graceful fallback to a newer model. The API call fails. For anything customer-facing or business-critical, that’s an outage.
Deprecated models are also likely to be less reliable than active ones in the months leading up to retirement, as Anthropic focuses engineering attention on current models. Early migration is worth it even before the deadline.
Two months is a comfortable window for most teams, but it goes quickly if it’s not on anyone’s sprint board. Worth getting it scheduled now.
Updates to this story
2 August 2026: Claude Opus 4.1 retires from the API on August 5 — three days to migrate
The retirement date covered in the original article is now three days away. As of August 5, 2026, claude-opus-4-1-20250805 will stop resolving on the Claude API, Claude Platform on AWS, and Microsoft Foundry. Any production system still calling that model string will begin returning errors immediately after the cutoff. This is no longer a planning concern; it is an operational one.
The recommended replacement remains claude-opus-4-8, as confirmed in the Anthropic model deprecations documentation. If your codebase passes temperature, top_p, or top_k parameters, remove them before migrating: those fields are deprecated on Claude Opus 4.7 and later and will return a 400 error when set to a non-default value. Steer sampling behavior through prompting instead.
The most common source of outages in a deprecation like this is not the main application but forgotten serverless functions, background workers, or archived microservices that still reference the old model name. Audit every pipeline touchpoint, not just the obvious ones.
One item to add to your backlog now: Claude Sonnet 4.5 retires on September 29, 2026, so teams that recently migrated from Sonnet 4.0 to 4.5 already have a second migration due within the quarter.
2 August 2026: Anthropic Workbench and experimental prompt-tools APIs retire August 17 — here’s what to export now
The August 5 Claude Opus 4.1 retirement covered below is now three days away, but a second deadline follows immediately after: the legacy Workbench at platform.claude.com/workbench shuts down on August 17, 2026, along with three experimental prompt-generation API endpoints.
The affected endpoints are /v1/experimental/generate_prompt, /v1/experimental/improve_prompt, and /v1/experimental/templatize_prompt. After August 17, calls to these will return errors. Any integration using them must be updated before then.
The replacement Workbench is already live in the new Build section of the Console. The key difference is that it is intentionally stateless: saved prompts, variables, and evals are not carried over. Your current draft stays in the browser only, and Anthropic will not retain your data server-side.
That makes the export step urgent. Saved prompts, completions, and evals from the legacy Workbench will not be accessible after the deadline. Anthropic says you can export data from the banner inside the legacy tool or under your Organizational Settings. Once the legacy version is retired, that data is gone.
Two actions before August 17: export everything you want to keep from the legacy Workbench, and audit any code calling the three experimental endpoints.
Sources: Anthropic platform release notes, Workbench help article.
31 July 2026: Claude Opus 4.1 API retirement is four days away, on 5 August 2026
Since this article published, the retirement date has gone from a distant deadline to an immediate one. claude-opus-4-1-20250805 hard-retires from the Claude API on August 5, 2026 — four days from now. Unlike some deprecations, there is no auto-redirect or graceful fallback: requests to retired models return errors.
The recommended migration target remains claude-opus-4-8. If you have not already switched, audit every location where the old model string is pinned — production code, serverless functions, CI/CD pipelines, and SDKs. Forgotten serverless functions and archived microservices are the most common source of post-retirement outages. Also note that claude-opus-4-8 does not accept non-default values for temperature, top_p, or top_k — those parameters now return HTTP 400, so remove them and rely on prompting instead.
A second deadline follows shortly after: on August 17, 2026, Anthropic is also retiring the experimental prompt tools endpoints (/v1/experimental/generate_prompt, /v1/experimental/improve_prompt, /v1/experimental/templatize_prompt) and the legacy Workbench. Saved prompts, variables, and evals from the legacy Workbench are not carried over automatically — export anything you need to keep via the banner or your Organizational Settings before that date.