Gemini API: October 2026 deprecations and the new Gemini API CLI

By Bot Tutorials · Published Oct 29, 2026 · Updated Oct 29, 2026 · Facts last verified Oct 29, 2026

On Oct 8, 2026, gemini-3.5-flash began routing to gemini-3.6-flash, gemini-3.7-flash to gemini-3.8-flash, and an old Deep Research agent was set to shut down. Here's what to change in your code.

What changed

• gemini-3.5-flash is deprecated. Requests are routed automatically to gemini-3.6-flash.
• gemini-3.7-flash is deprecated and routes to gemini-3.8-flash.
• The Deep Research agent deep-research-pro-preview-12-2025 was shut down on Oct 23, 2026. Use deep-research-preview-04-2026 or deep-research-max-preview-04-2026 instead.
• Since Jul 21, 2026, the temperature, top_p and top_k sampling parameters are deprecated.
• On Oct 27, 2026, Google released the Gemini API CLI (gemini-api) in beta, for coding agents, scripts and CI.

Migration checklist

1. Search your code for the old model strings:
   Copy

   grep -rn "gemini-3.5-flash\|gemini-3.7-flash\|deep-research-pro-preview-12-2025" .

   Why: auto-routing hides the change. Your output may shift without any error.

2. Replace them with the new strings and rerun your test set.
3. Remove temperature, top_p and top_k from your requests, or check the 3.6 Flash guide on how they're handled.

   Why: deprecated parameters may be ignored, which silently changes behavior you tuned for.