Preflight: distinguish Free SKU, subscription quota, and regional service capacity failures

Problem

Preflight and deployment errors can conflate three different causes:

• an unsupported or unsuitable Free SKU;
• subscription quota exhaustion; and
• generic regional service capacity (InsufficientResourcesAvailable).

These require different remediation. In a recent clean Template 19 validation, Azure AI Search Standard failed in one region with InsufficientResourcesAvailable, while the same Standard deployment succeeded in another region. That was regional capacity, not an attempted Free tier deployment.

Suggested improvement

Extend the preflight output and troubleshooting guide to classify capacity failures by resource provider, SKU, region, and error code. Suggested messages:

• SKU_UNSUPPORTED: selected SKU is not supported by Template 19.
• QUOTA_EXCEEDED: subscription quota is insufficient; link to quota request guidance.
• REGIONAL_CAPACITY_UNAVAILABLE: the requested paid SKU is valid but cannot currently be provisioned in the region; recommend checking an alternative region.

For Azure AI Search, print the requested SKU explicitly before deployment and preserve the service request ID only in local diagnostic output.

Expected result

Users should be able to answer "Free tier, my quota, or regional capacity?" directly from preflight/deployment diagnostics.

Start by locating the Template 19 preflight and deployment diagnostics plus the troubleshooting guide, then trace Azure AI Search handling for SKU and regional errors. Use the reported case where Standard succeeds in one region and fails with InsufficientResourcesAvailable as a validation scenario. Done means diagnostics distinguish SKU_UNSUPPORTED, QUOTA_EXCEEDED, and REGIONAL_CAPACITY_UNAVAILABLE, show the requested SKU, and keep request IDs in local output.