Google Gemini gemini-3-pro-preview model returns 404 NotFoundError after March 9, 2026 deprecation, breaking litellm/dspy pipelines
gemini-3-pro-preview was shut down March 9, 2026. Replace with gemini-3.1-pro-preview (direct successor). Also: gemini-3-flash-preview is the preview alias for gemini-3.5-flash — move to the stable name. For cost-sensitive summarization tasks, gemini-3.1-flash-lite ($0.25/$1.50 per 1M tokens) is the price-performance option. All model codes use dots not hyphens for version numbers (e.g. gemini-3.1-pro-preview, not gemini-3-1-pro-preview). litellm prefix remains 'gemini/' for all.