overloaded_error 🔌 API

LLM API: overloaded_error (529) / The server is overloaded / Service unavailable — model temporarily overloaded

The provider is temporarily at capacity; the request was rejected even though your key and quota are fine.

Seen on: REST API

Meaning

Overload errors (HTTP 529 at Anthropic, 503/“The engine is currently overloaded” elsewhere) are transient. Retry with exponential backoff and jitter, and consider fallback models or batch/off-peak processing.

Common causes

  • Provider capacity spike
  • Very large requests during peak hours
  • No retry/backoff in the client

⚡ Quick fix

  1. Retry with exponential backoff and jitter (SDKs do this; raise max_retries)
  2. Use a fallback model or region
  3. Use batch processing for non-urgent work

Detailed fix by platform

Python

  1. client = anthropic.Anthropic(max_retries=5) # SDK retries 429/5xx/529 with backoff

How to diagnose

  1. Status — 529/503 vs 429
  2. Timing — Peak periods?
  3. Retries — Backoff configured?

🔧 Still not fixed?

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