ERROR CODES / ENGLISH
529 Overloaded: Anthropic capacity is full
What Anthropic's 529 overloaded error means, when waiting is enough, and how to tell provider capacity from a relay channel limit.
Reviewed 2026-11-13 · ERROR CODES / 529 · Chinese detail: 完整中文页
What it means
529 is Anthropic's specific way of saying "my capacity is full". It has nothing to do with your key, your balance, or your parameters. Wait, or switch channels.
{"type":"error","error":{"type":"overloaded_error","message":"Overloaded"}}
// Relayed by a relay
上游负载已饱和，请稍后再试 (529)The relay message says upstream load is saturated and asks you to try again later.
Common causes
| Share | Cause |
|---|---|
| 70% | Anthropic server capacity is insufficient (usually at peak hours) |
| 20% | The relay's channel is maxed out |
| 10% | Your requests are too dense and were deprioritized |
How to confirm
Wait 30-60 seconds and retry: 529 recovers quickly. If the retry passes, you were seeing provider capacity. If the same model through another site or group passes, the channel was the limit. If all Claude models return 529 at the same time, the cause is Anthropic.
Fix
Short term:
- Wait 30-60 seconds and retry. 529 recovers quickly.
- Switch model tier:
claude-opus-5-5is more likely to be overloaded thanclaude-haiku-5-5. - On a relay, switch channel group.
Long term:
If your business is sensitive to availability, do not put all your eggs in one channel. The relay comparison data on this site lists more than 60 providers with an online rate above 99%.
If it still fails
| Symptom | Responsible party |
|---|---|
| All Claude models return 529 | Anthropic |
| Only one site's Claude models return 529 | That site's channel |
| Only opus returns 529, sonnet is fine | Anthropic's high-end model capacity |
| Normal late at night (early morning US West time) | Peak-hour capacity |
529 is not 503. 529 is Anthropic-specific overload; 503 is a generic service-unavailable status and may mean the site itself is down.
General guidance, not a statement about any specific provider. For measured data, see the relay directory and method.