ValidationException on the model ID — what does it actually mean?

[akash-coded]

I get this on a model that is definitely enabled in the console:

ValidationException: Invocation of model ID anthropic.claude-sonnet-4-5-20250929-v1:0
with on-demand throughput isn't supported. Retry your request with the ID or ARN of
an inference profile that contains this model.

Model access shows as granted, the region is right, and the same code works for a colleague. What am I missing?

[akash-coded]

Your colleague is passing an inference profile ID; you are passing the bare model ID. The error says so, but the wording buries it.

What is going on. Many models are not served on-demand under their plain model ID. They are invoked through a cross-Region inference profile, whose ID carries a geography prefix — us., eu. and others depending on the geography.

anthropic.claude-sonnet-4-5-20250929-v1:0        ← the model
us.anthropic.claude-sonnet-4-5-20250929-v1:0     ← the profile you actually invoke

Find what your region offers:

aws bedrock list-inference-profiles --region us-east-1 \
  --query 'inferenceProfileSummaries[].[inferenceProfileId,status]' --output table

Use that value as modelId.

The part that catches people next. A geographic profile routes across several regions, and you need model access in every region it routes to — not just the one you are calling from. A profile fanning out to us-east-1, us-east-2 and us-west-2 needs access granted in all three, or you get an AccessDeniedException that appears intermittent because it depends on where the request landed.

IAM. If you scope Bedrock permissions, grant both ARNs — the profile and the underlying foundation models:

"Resource": [
  "arn:aws:bedrock:us-east-1::foundation-model/anthropic.claude-*",
  "arn:aws:bedrock:us-east-1:123456789012:inference-profile/us.anthropic.claude-*"
]

Granting only the profile is a common cause of a confusing denial.

Related. Troubleshooting covers the other errors this curriculum produces; IAM for agents has the full policy shapes.