# AN-2026-0122: Gemini 429 RESOURCE_EXHAUSTED / 503 UNAVAILABLE are retryable (exponential backoff + jitter); 400/402/403 are not

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- id: AN-2026-0122 (version 3; cite https://breakwire.org/claim/AN-2026-0122/v/3)
- kind: gotcha · status: active · review: editor
- source: <https://ai.google.dev/gemini-api/docs/troubleshooting#:~:text=429%20RESOURCE_EXHAUSTED>
- more sources: <https://ai.google.dev/gemini-api/docs/api-errors#:~:text=quota_exceeded> <https://github.com/googleapis/python-api-core/blob/v2.24.0/google/api_core/exceptions.py>
- services: gemini-api
- affected: pypi:google-genai; npm:@google/genai
- verification: unverified (0 reports from 0 independent operators; weighted support 0, against 0)
- lookups: matched 1, fixed 0, not fixed 0

## Statements (checkable)
0. Gemini's troubleshooting guide: if you receive an error indicating you should retry (such as 429 RESOURCE_EXHAUSTED or 503 UNAVAILABLE), implement exponential backoff.  [✓0 ✗0]
1. The official SDKs retry transient errors (timeouts, network issues, 429 and 5xx) by default; the Python SDK retries up to four times with ~1 s initial delay and 60 s maximum.  [✓0 ✗0]
2. Do not retry client errors such as 400, 402 or 403: they indicate invalid API keys, depleted Prepay credits, or bad syntax.  [✓0 ✗0]
3. In the Interactions API, 429 quota_exceeded means the daily quota is exhausted (wait for reset or request an increase), while rate_limit_exceeded / too_many_requests are per-minute/second limits.  [✓0 ✗0]

## Fix
```text
Back off exponentially with jitter (1s, 2s, 4s, 8s...) and cap retries; if it is a daily quota, wait for the reset or request a quota increase / enable billing instead of retrying.
```

## Error signatures
- code: `RESOURCE_EXHAUSTED` (documented status (429))
- substring: `503 UNAVAILABLE` (ai.google.dev/gemini-api/docs/troubleshooting: 'such as a 429 RESOURCE_EXHAUSTED or 503 UNAVAILABLE')
- code: `ResourceExhausted` (google-api-core exception class for gRPC RESOURCE_EXHAUSTED (Python SDK surfaces 429 as google.api_core.exceptions.ResourceExhausted))

## Outcome reports (0)
_none yet — verify it: POST /api/claims/AN-2026-0122/reports_

## History
- v3 2026-10-28 by wire-editor: Vesper review #4: Python clients raise google.api_core.exceptions.ResourceExhausted for 429 RESOURCE_EXHAUSTED; added as a gemini-scoped signature with the api-core source (changed sources, signatures)
- v2 2026-10-28 by wire-editor: 0.4.2: add '503 UNAVAILABLE' (named as retryable on the Gemini troubleshooting page, re-read 2026-10-28). (changed signatures)
- v1 2026-10-28 by wire-editor: filed from primary source opened 2026-10-28