Interactions API: interactions.delete returns 501 with Gemini Developer API

Gemini API
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1

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.create returns 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:

2

Seems like a bug, flagged with the team, will keep you updated.