Deep Research API - Follow up questions and interactions

Gemini API
1

The deep research api 04-2026 version works fine until I ask a followup and I keep getting errors. I tired switching in 3.1-pro-preview as per the documentation - https://ai.google.dev/gemini-api/docs/deep-research - but it keeps failing

2

Thank you for reporting! Working on a fix

3

Should be fixed, can you please try again.

4

It is not working. It keeps telling me to change my api key - and when I did it got an error 400

5

Could you share your code snippet please? Will try to reproduce it

6

For this application I have used a low code builder so I don’t have any code snippets but I reduced the curl command to its bare minimum as if it wasn’t a followup and I kept the api key the same and it worked fine. After this I introduced previous_interaction_id and used a previous id from a query ran under the old deep research api, it failed. I’ll try an interaction id from a query run on the new deep research api

7

can I use the deep research agent for follow up queries or do i have to follow what is on the documentation page using gemini 3.1 pro preview? I’ve done some testing the last week, and both seem to work but not reliably so

8

What I mean is for follow up questions does it have to be

"model": "gemini-3.1-pro-preview",
    "previous_interaction_id": "COMPLETED_INTERACTION_ID"

or can it be 

"model": "deep-research-preview-04-2026",
    "previous_interaction_id": "COMPLETED_INTERACTION_ID"