Problem (one or two sentences)

Requests to Claude Sonnet 4.5 in Google Vertex AI return

404 [
{"error":
{"code":404,"message":"Publisher Model projects/PROJECT-NAME-HERE/locations/us-east5/publishers/anthropic/models/claude-4.5-sonnet not found.","status":"NOT_FOUND"}
}
]

For what it's worth, in the Vertex AI Console they identify the model as claude-sonnet-4-5@20250929

from anthropic import AnthropicVertex

client = AnthropicVertex(region="global", project_id="YOUR_PROJECT_ID")
message = client.messages.create(
 max_tokens=1024,
 messages=[{"role": "user", "content": "Hello! Can you help me?"}],
 model="claude-sonnet-4-5@20250929"
)
print(message.content[0].text)

Context (who is affected and when)

Users of Sonnet 4.5 using Google Vertex AI Provider

Reproduction steps

Select claude-4.5-sonnet on the Vertex AI Model Provider

Expected result

The command works

Actual result

A 404 error is returned

Variations tried (optional)

No response

App Version

v3.28.11

API Provider (optional)

Google Vertex AI

Model Used (optional)

Claude Sonnet 4.5

Roo Code Task Links (optional)

No response

Relevant logs or errors (optional)