Google announced a breaking change to the Gemini Interactions API. Starting May 26, the new version becomes the default, and on June 8, the old version will be fully removed. After that, any requests using Python or JavaScript SDK version 1.x.x will fail immediately.
Developers need to update two parts of their code:
First, how they extract responses. The old outputs array is deprecated — all content reading now moves to the more granular steps array. Whether you're reading model-generated text or function calling results, you'll need to rewrite parsing logic to match the new structure.
Second, how they configure output format. The previously scattered MIME type declarations and image generation parameters (image_config) are now consolidated into a single response_format parameter. This unification brings a new capability: developers can pass an array to response_format, letting the model output text and audio (or other multimodal results) in a single request.
SDK users can upgrade to version 2.0.0 or higher to automatically handle the switch. REST API users can add an Api-Revision: 2026-05-20 header to test the new version early. After May 26, when the new version becomes default, developers who haven't finished updating can use the 2026-05-07 header to temporarily revert — but only until June 8, when the old version is cut off for good.