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

[belbas]

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: Interactions API: client.interactions.cancel returns 404 "Method not found" #1971.

Documentation:

• https://ai.google.dev/gemini-api/docs/interactions-overview
• https://ai.google.dev/gemini-api/docs/background-execution#cancellation-and-deletion

[a2105z]

Hi there, I am new here, but let me take a stab at this.
@Venkaiahbabuneelam -> do you mind if I do, I notice you had a lot assigned to you, so I would have thought maybe this one is one I can try out?

[a2105z]

Thanks @belbas for the clear reproduction, and @Venkaiahbabuneelam for taking this on.

I'd like to help investigate and open a PR for any SDK-side improvements we can make here. From an initial look:

• The SDK is issuing DELETE /v1beta/interactions/{id} as documented.
• Create/get succeed; only delete returns 501 Not Implemented, including with an explicit Api-Revision header.
• Related: Interactions API: client.interactions.cancel returns 404 "Method not found" #1971 (interactions.cancel) was also a Gemini Developer API backend failure with a correct SDK path — and in that thread, delete previously succeeded.

I'll dig further on the client side (retry behavior around 501, request construction) and open a PR if there's an actionable SDK fix. If this turns out to be purely server-side, happy to capture that clearly in the PR / comments so it can be routed internally.

Please let me know if you'd prefer I hold off — I noticed this is already assigned.

[a2105z]

Opened a PR with the SDK-side retry fix: #2809

Happy to adjust based on maintainer feedback. As noted there, the 501 response itself still looks like it needs a backend fix.

[Venkaiahbabuneelam]

Hey @belbas, thanks for reaching out us!
I have checked your code and did not encounter any errors, we successfully received an OK response with versions 2.10.0 and 2.16.0.

Please find the attached images.

Thanks