* **Gemini 2.5 Pro deprecation**:
[`gemini-2.5-pro`](/docs/models/gemini-2.5-pro) is
[deprecated](/docs/deprecations#gemini-2.5-pro-models) and is no longer
available to select in Google AI Studio. Effective December 1, 2026, all API
requests to `gemini-2.5-pro` will automatically route to
[`gemini-3.8-flash`](/docs/models/gemini-3.8-flash) and be billed at
[Gemini 3.8 Flash rates](/docs/pricing#gemini-3.8-flash). Before December 1,
2026, update your model string to `gemini-3.8-flash` and review the
[Gemini 3.8 Flash migration guide](/docs/whats-new-gemini-3.8#migrate-to-gemini-3-8-flash).
Breaking API changes include function calling and `thought_signature`
validation, `thinking_level` replacing `thinking_budget`, and removed
sampling parameters and prefilled model turns.
* **Gemini 2.5 Flash deprecation**:
[`gemini-2.5-flash`](/docs/models/gemini-2.5-flash) is
[deprecated](/docs/deprecations#gemini-2.5-flash-models) and is no longer
available to select in Google AI Studio. Effective December 1, 2026, all API
requests to `gemini-2.5-flash` will automatically route to
[`gemini-3.5-flash-lite`](/docs/models/gemini-3.5-flash-lite) and be billed
at [Gemini 3.5 Flash-Lite rates](/docs/pricing#gemini-3.5-flash-lite).
Before December 1, 2026, update your model string to `gemini-3.5-flash-lite`
and review the
[Gemini 3.5 Flash-Lite migration guide](/docs/whats-new-gemini-3.6#migrate-to-gemini-3-5-flash-lite).
Breaking API changes include function calling and `thought_signature`
validation, `thinking_level` replacing `thinking_budget`, and removed
sampling parameters and prefilled model turns.