Interactions API: interactions.delete returns 501 with Gemini Developer API
Description
Deleting a completed, stored interaction consistently returns HTTP 501 when
using the Gemini Developer API with API-key authentication.
Interaction creation and completion work normally. Only the cleanup request
fails.
Environment
google-genai: 2.16.0- Also reproduced with: 2.10.0
- Python: 3.11.8
- Authentication: Gemini Developer API key, not Vertex AI
- Endpoint:
https://generativelanguage.googleapis.com/v1beta - Model:
gemini-3.5-flash-lite
Minimal reproduction
import os
from google import genai
client = genai.Client(api_key=os.environ["GEMINI_API_KEY"])
interaction = client.interactions.create(
model="gemini-3.5-flash-lite",
input="Reply with OK.",
store=True,
)
client.interactions.delete(id=interaction.id)
Expected behavior
The interaction is deleted successfully, as documented for
DELETE /v1beta/interactions/{id}.
Actual behavior
The API returns:
DELETE https://generativelanguage.googleapis.com/v1beta/interactions/{id}
HTTP/1.1 501 Not Implemented
The SDK retries the request and eventually raises InternalServerError.
The same 501 response occurs when the documented revision header is passed
explicitly:
client.interactions.delete(
id=interaction.id,
extra_headers={"Api-Revision": "2026-05-20"},
)
Additional information
interactions.createreturns HTTP 200.- The interaction completes successfully before deletion is attempted.
- The issue occurs with both SDK 2.10.0 and 2.16.0.
- This is a foreground model interaction, not a background managed-agent run.
- A related server-side issue exists for
interactions.cancel: #1971.
Documentation: