Platform Gotchas — Top 10

1. OSS models require "trainingType": "globalStandard" in the request body — undocumented, and all OSS FT jobs fail without it.

1. Model catalog fine_tune flag is wrong for OSS models — API returns fine_tune = false for all OSS models despite being FT-supported. Hardcode the supported list.

1. Older SDK versions may fail on /v1/ project endpoints — client.files.create() throws "API version not supported" with older openai package versions. Upgrade to openai>=1.0 and use the /v1/ project endpoint (preferred). If you must use an older SDK, fall back to REST API with the non-project /openai/ endpoint.

1. ARM "Succeeded" doesn't mean deployment is ready — provisioningState: Succeeded but data plane returns DeploymentNotReady indefinitely. Delete and recreate the deployment, then wait ~5 minutes.

1. OSS FT deployments may fail with InternalServerError — use the correct provider-specific model.format (e.g., "Mistral AI" not "OpenAI") and try capacity=100.

1. OSS FT inference hits "Failed to load LoRA" intermittently — deploy with capacity ≥ 100, use 8+ retries with exponential backoff, and wait 2+ minutes after deployment before first call.

1. ARM REST and az cognitiveservices use different format strings for OSS models — ARM uses provider names ("Microsoft", "Meta"), CLI uses "OpenAI-OSS" for all OSS. Mixing them produces HTTP 500.

1. Content safety false positives on entity extraction data — PII-dense data (medical records, legal docs, resumes) can trigger "Hate/Fairness" blocks at deployment time. Remove problematic document types.

1. FT deployments at capacity=1 are severely rate-limited (~1 RPM) — evaluating 10 samples takes ~10 minutes. Use capacity ≥ 100 for eval workloads and exponential backoff.

1. Wrong resource endpoint is a silent killer — jobs submitted to the wrong Foundry resource succeed via API but don't appear in the portal. Always verify the endpoint matches your Foundry project.