Triaging agent workflows fail with 404 on gemini-2.5-pro via Gemini Developer API

[doughayden]

🔴 Required Information

Describe the Bug:

The two GitHub Actions workflows that run the issue and PR triaging agents in contributing/samples/ fail with a 404 NOT_FOUND error from the Gemini Developer API. The agents call gemini-2.5-pro via google-genai with GOOGLE_GENAI_USE_VERTEXAI=0, and the API returns that the model is not found for API version v1beta.

Steps to Reproduce:

1. Wait for the 6-hour cron on .github/workflows/triage.yml, or open any issue on this repo
2. Same for .github/workflows/pr-triage.yml on any PR event
3. Workflow fails in the "Run Triaging Script" step

Expected Behavior:

The triaging agent runs and applies labels / owners as designed.

Observed Behavior:

The agent throws on the first generateContent call. Identical error in both workflows:

google.genai.errors.ClientError: 404 NOT_FOUND. {'error': {'code': 404, 'message': 'models/gemini-2.5-pro is not found for API version v1beta, or is not supported for generateContent. Call ListModels to see the list of available models and their supported methods.', 'status': 'NOT_FOUND'}}

Environment Details:

• ADK Library Version: whatever pip install google-adk resolves at workflow runtime (workflow installs latest, no pin)
• OS: GitHub Actions ubuntu-latest
• Python Version: 3.11

Model Information:

• Using LiteLLM: No
• Model: gemini-2.5-pro, hardcoded in contributing/samples/adk_triaging_agent/agent.py:247 and contributing/samples/adk_pr_triaging_agent/agent.py:223

---

🟡 Optional Information

Regression:

Not investigated. Recent failed runs and an earlier successful run for reference:

• Issue Triaging Agent failures: run id 25818811580 (schedule, 2026-05-13T18:34:48Z), run id 25540877932 (the oldest failure with this same 404 within the last 100 runs, 2026-05-08T06:33:52Z)
• Issue Triaging Agent prior success: 2026-05-08T01:21:11Z
• PR Triaging Agent failures: run id 25818804655 (pull_request_target, 2026-05-13T18:34:39Z)
• PR Triaging Agent prior success: 2026-05-07T23:59:39Z

Logs:

Trimmed traceback from run id 25818811580:

2026-05-13 18:35:28,489 - INFO - google_llm.py:208 - Sending out request, model: gemini-2.5-pro, backend: GoogleLLMVariant.GEMINI_API, stream: False
...
File "/opt/hostedtoolcache/Python/3.11.15/x64/lib/python3.11/site-packages/google/genai/_api_client.py", line 1515, in _async_request_once
    await errors.APIError.raise_for_async_response(response)
google.genai.errors.ClientError: 404 NOT_FOUND. {'error': {'code': 404, 'message': 'models/gemini-2.5-pro is not found for API version v1beta, or is not supported for generateContent. Call ListModels to see the list of available models and their supported methods.', 'status': 'NOT_FOUND'}}

Additional Context:

Sibling sample agents in the same repo with similar workflows provide useful contrast:

Failing, model hardcoded to gemini-2.5-pro with GOOGLE_GENAI_USE_VERTEXAI=0:

• triage.yml running adk_triaging_agent
• pr-triage.yml running adk_pr_triaging_agent

Passing, model read from LLM_MODEL_NAME env var (defaults to gemini-2.5-flash in settings.py), with GOOGLE_API_KEY set and GOOGLE_GENAI_USE_VERTEXAI unset:

• issue-monitor.yml running adk_issue_monitoring_agent
• stale-bot.yml running adk_stale_agent

Different backend, not affected:

• discussion_answering.yml running adk_answering_agent with GOOGLE_GENAI_USE_VERTEXAI=1, so the call lands on Vertex (aiplatform.googleapis.com)

Per https://ai.google.dev/gemini-api/docs/deprecations, gemini-2.5-pro is documented as supported through Oct 16, 2026.

Two other sample agents hardcode gemini-2.5-pro:

• contributing/samples/adk_answering_agent/agent.py (currently routed through Vertex via its workflow so unaffected)
• contributing/samples/adk_issue_formatting_agent/agent.py (not currently wired to any workflow)

How often has this issue occurred?:

Always (100%) since approximately 2026-05-08, when both workflows started returning the same 404 within ~1 hour of each other (Issue Triaging Agent first observed failure run id 25540877932 at 2026-05-08T06:33:52Z; PR Triaging Agent first observed failure run id 25538353557 at 2026-05-08T05:19:35Z).

[llalitkumarrr]

Hello @doughayden ,

This issue relates to an internal bot used to help maintain the repository. Since it does not affect google-adk in any way, hence I am closing this issue.