What this model error usually means
ByteDance Seed: Seed 1.6 Flash returning 400 / model capability unsupported means you should first confirm whether model ID bytedance-seed/seed-1.6-flash is visible for this ByteDance Seed key, then separate permission, context, capability, rate limit, or route issues.
- Model: bytedance-seed/seed-1.6-flash
- Provider: ByteDance Seed
- Status code: 400