What happens on AI model shutdown day

On shutdown day the retired id is no longer served. OpenAI says it is no longer accessible. Anthropic, Gemini, and Bedrock say requests fail or the endpoint is gone. Azure either upgrades the deployment or stops it, depending on versionUpgradeOption. A 400 from a rejected field is a different event: that happens when you call the replacement with old settings.

Last reviewed October 20, 2026. Publisher: SunsetDiff.

Steps

Confirm the calendar. Use the platform page for the host you call. Azure, Bedrock, and Vertex do not inherit the first-party day.
Expect the retired id to fail. Read the provider wording below. Do not invent an HTTP status the official page does not print.
If you already switched, read the error pages. A replacement can return 400 for temperature, max_tokens, or tool settings the old model accepted.

OpenAI

OpenAI says that at shut down the model or endpoint is no longer accessible. Sunset and shut down mean the same thing on that page. The deprecations page does not print an HTTP status or an error sentence for that moment.

The model has been deprecated page is the place for the sentence a public issue recorded after a model was removed. It says the deprecations page itself does not print that sentence. The October 23, 2026 batch is OpenAI model IDs shutting down October 23, 2026.

Source: OpenAI deprecations , checked October 20, 2026.

Anthropic

Retired means the model is no longer available. Requests to retired models fail. Requests past the retirement date fail. The deprecations page does not name an HTTP status for that failure.

A different failure is a live model rejecting an old field. Those are HTTP 400, and they are documented on the request errors for claude-sonnet-5-5, with the migration guide as the source.

Source: Anthropic model deprecations , checked October 20, 2026.

Gemini API

The Gemini deprecations page says that once a model is shut down it is completely turned off and the endpoint is no longer available. It does not print one error sentence for every model.

Firebase's model page says Gemini 1.0 and Gemini 1.5 are already shut down, and that requests to those models return a 404. That sentence is about those generations. It does not say every later id returns 404.

This model is no longer available quotes the 404 sentence recorded for gemini-2.0-flash, which shut down June 1, 2026. Use that page for the sentence. Do not assume every later Gemini id returns the same text.

Sources: Gemini API deprecations , Firebase AI Logic models , checked October 20, 2026.

Amazon Bedrock

After the EOL date, Bedrock says the model is removed from the Regions on that row and requests to it fail, unless you have a private arrangement with the provider. Migration does not happen automatically. You change the model id in the application before EOL.

The legacy page adds that state can differ by Region. Check ListFoundationModels or GetFoundationModel in the Region you call and read modelLifecycle.

Sources: Bedrock model lifecycle , Bedrock legacy lifecycle , checked October 20, 2026.

Azure OpenAI

What Azure does depends on the deployment upgrade option. OnceNewDefaultVersionAvailable and OnceCurrentVersionExpired upgrade the deployment. NoAutoUpgrade never upgrades. At retirement that deployment stops working, and you have to point the code at a deployment that has not expired.

The model versions page says that if you opted out of automatic upgrades, the deployment stops accepting requests and returns errors after the model is retired. That page does not print a status code or an error sentence. Microsoft's HTTP troubleshooting table lists 404 for a deployment name that does not exist, which is a separate case from a dated retirement.

Sources: Working with Azure OpenAI models , Azure model versions , Azure OpenAI HTTP errors , checked October 20, 2026.

Related SunsetDiff pages

All guides

Questions

Is shutdown day always HTTP 404?

The OpenAI, Anthropic, and Bedrock retirement pages do not say that. Firebase says Gemini 1.0 and 1.5 return a 404. The 404 sentence SunsetDiff quotes for gemini-2.0-flash is on the request error page.

Why did I get HTTP 400 before shutdown day?

The replacement is up, and it rejected a field. Start at the request errors index. That is not the retired-id failure.