Does new interaction API support vertex ai?

[danhnguyen8391]

I tried interaction API with vertex ai but get error 404. For the same code, I try with AI studio API key, it works. Seem like this new API does still not support vertex ai?

[adk-bot]

Response from ADK Answering Agent (experimental, answer may be inaccurate)

TLDR: Yes, the Interaction API supports Vertex AI, but it requires a different configuration than the AI Studio API key. The 404 error you're seeing is likely due to an authentication or configuration issue. Please ensure you have authenticated for Vertex AI and set the correct environment variables.

---

Hello! Thanks for your question.

The ADK is designed to work with both the Gemini API (used by AI Studio) and the Vertex AI API. However, they use different authentication and configuration setups, which is likely the cause of the 404 error you are encountering.

Here are the key differences and steps to ensure your environment is set up correctly for Vertex AI:

1. Authentication:

   • AI Studio uses an API key (GOOGLE_API_KEY).
   • Vertex AI uses your Google Cloud user credentials. You must authenticate by running this command in your terminal:

     gcloud auth application-default login

2. Environment Variables: To tell the ADK to use Vertex AI instead of the Gemini API, you must set the following environment variable. [1, 2]

   export GOOGLE_GENAI_USE_VERTEXAI=TRUE

By default, if GOOGLE_GENAI_USE_VERTEXAI is not set or is FALSE, the ADK will attempt to use the Gemini API with an API key. [2, 3]

To resolve the 404 error, please verify that you have:

• Run gcloud auth application-default login successfully.
• Set GOOGLE_GENAI_USE_VERTEXAI to TRUE in your environment.
• Ensured that your Google Cloud project has the Vertex AI API enabled.

Following these steps should correctly configure the ADK to use your Vertex AI setup. Let us know if you continue to experience issues.

[1] https://google.github.io/adk-docs/streaming/dev-guide/part1/
[2] https://google.github.io/adk-docs/agents/config/
[3] https://google.github.io/adk-docs/get-started/quickstart/

[danhnguyen8391]

My vertex ai service account still works well when I use generated content API that means the setup is not a problem. It only does not work when I use interaction API.

[patrickloeber]

Hi, Patrick here from the Gemini API team. No, the Interaction API is currently not available in Vertex AI. It's in our roadmap, we expect to bring Interactions API to VertexAI in the next couple of months.

[joeyhotz]

Also awaiting this. we we're incurring lots of unnecessary costs using the global endpoint because inputs were more likely to not hit the cache on subsequent calls, I'm assuming the interactions API with its previous interaction storage means more cache hits on the global endpoint? That would be great.

But we use vertex because we're an organisation.

[scs640]

@patrickloeber any update on this? I am still seeing the same results as the posters above - "BadRequestError: Error code: 400
Unsupported model interaction: gemini-3.5-flash" on any model I actually want to use. Very frustrating, as an organisation without Google workspace, we do not have access to AI Studio API keys... and anyway, why would we want to diverge from Google's Enterprise Vertex AI offering??

[elaineg]

Hi all, I'm Elaine on the Vertex Gemini API product team. Excited to see the demand for us to bring the base models to the Interactions API on Vertex. We anticipate that the 3.5 and 3.6 Gemini models will be available publicly in early September.

[elaineg]

Hi @markrubio-TU, I just tested the Antigravity agent antigravity-preview-05-2026 on Vertex and I wasn't able to reproduce a 500 API error. Are you still experiencing this issue?

[markrubio-TU]

I no longer experience this error. Thanks for checking. A follow up
question though, when is this going to be GA in your roadmap? Thanks