claude-sonnet-4-5 shutdown date: Nov 30, 2026 (Vertex AI)

The error you get from November 30, 2026

What Vertex AI answers a call to claude-sonnet-4-5 once the model is gone, as recorded from real responses:

HTTP 404

{"error":{"code":404,"message":"Publisher model `projects/{project}/locations/{region}/publishers/google/models/claude-sonnet-4-5` was not found or your project does not have access to it. Ensure you are using a valid model name and that the model is available in the specified region.","status":"NOT_FOUND"}}

Facts

API: Vertex AI aiplatform.googleapis.com
Model: claude-sonnet-4-5
Released: September 29, 2025 (models.dev)
Kind: Model retirement
Takes effect: November 30, 2026
Calls after that day: Fail
Source: Deprecations page
Last updated: November 5, 2026
Verified: November 6, 2026, against Vertex AI's own pages

Questions

When does claude-sonnet-4-5 shut down?

Calls to the model claude-sonnet-4-5 on Vertex AI stop working on November 30, 2026.

What happens to calls after November 30, 2026?

They fail from that day.

What error does claude-sonnet-4-5 return once it is shut down?

Vertex AI answers HTTP 404: "Publisher model `projects/{project}/locations/{region}/publishers/google/models/claude-sonnet-4-5` was not found or your project does not have access to it. Ensure you are using a valid model name and that the model is available in the specified region.". Send another model to fix it.

When was claude-sonnet-4-5 released?

claude-sonnet-4-5 was released on September 29, 2025, according to models.dev.

How do I find the calls this hits in my code?

Okapi reads your repository, finds the calls this change hits and opens a pull request with the fix. It never commits to your branches: every change comes as a pull request you review.

claude-sonnet-4-5 on other APIs 2

Nov 30, 2026 Azure AI Foundry claude-sonnet-4-5Model retirement Stops workingin 24 days
Nov 30, 2026 Anthropic claude-sonnet-4-5Model retirement Stops workingin 24 days

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Is your code calling this?

Okapi finds the calls this change hits in your repo and opens the pull request with the fix before November 30, 2026.

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Vertex AI claude-sonnet-4-5 model retirement