Gemini Image API – 503 UNAVAILABLE (high demand) on gemini-3-pro-image-preview

Gemini API
,
1

Hello Google Gemini API Support,

We are experiencing repeated 503 errors when calling the image generation endpoint with our API key.

Endpoint
POST https://generativelanguage.googleapis.com/v1beta/models/gemini-3-pro-image-preview:generateContent

Model
gemini-3-pro-image-preview

Error received (example)
HTTP/1.1 503 Service Unavailable
503 UNAVAILABLE. {'error': {'code': 503, 'message': 'This model is currently experiencing high demand. Spikes in demand are usually temporary. Please try again later.', 'status': 'UNAVAILABLE'}}

Context

  • Our service generates a PNG architecture diagram (response modalities: TEXT + IMAGE).

  • We are seeing this intermittently, sometimes repeatedly, across multiple attempts and sessions.

  • We would like guidance on best practices to avoid/mitigate this (recommended retry strategy, backoff, quotas, or alternative model/endpoint).

Questions

  1. Is this behavior expected for gemini-3-pro-image-preview (capacity/preview limitation)?

  2. Do you recommend a different image-capable model for production workloads with better availability/SLA?

  3. Are there any per-key quota/rate limits or regional constraints that could increase 503 frequency?

  4. Should we implement a specific exponential backoff + Retry-After handling, and what maximum wait is recommended?

  5. Can you confirm whether there is a known incident affecting this model at the moment, and any ETA/updates?

If you need additional details (request ID, project ID, headers, or timestamps), tell us what to capture and we will provide it.

Thank you,
Abid Aymen

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