Daily · · Gemini API · 🌶️🌶️Worth a lookMedium: worth a look Why: Old model names reroute and rebill
Gemini 2.5 Pro and Flash reroute on Dec 1
Action needed: Google deprecated gemini-2. and gemini-2. in the Gemini API on Nov 2, 2026. From Dec 1, 2026, requests to them go to newer models automatically and are billed at those models’ rates.
What changed
Your old model string keeps answering after Dec 1, but a different model answers. Both models are already gone from the model picker in Google AI Studio. From Dec 1, 2026, every API request that names one of them is routed to its replacement.
Where each one goes
gemini-2.routes to5-pro gemini-3., billed at Gemini 3.8 Flash rates.8-flash gemini-2.routes to5-flash gemini-3., billed at Gemini 3.5 Flash-Lite rates.5-flash-lite
Why a new model string may not be enough
Google lists breaking API changes on the replacements. Function calling and thought_ validation change, thinking_ replaces thinking_, and sampling parameters and prefilled model turns are removed. Google’s migration guides for each replacement walk through these changes.
What to do
- Find every app, script and agent that names
gemini-2.or5-pro gemini-2..5-flash - Before Dec 1, 2026, switch the model string and follow the matching migration guide.
- Check the replacement’s rates on Google’s pricing page so the new bill holds no surprises.
Source: Gemini API release notes, Nov 2, 2026 · Google docs: Gemini API deprecation schedule