# httpx.ConnectError: [Errno 111] 连接被拒绝

- **ID:** `python/httpx-connect-error-all-connection-attempts-failed`
- **领域:** python
- **类别:** network_error
- **验证级别:** ai_generated
- **修复率:** 80%

## 根因

目标主机/端口未接受 TCP 连接；服务器已关闭、端口错误或被防火墙阻止。

## 版本兼容性

| 版本 | 状态 | 引入 | 弃用 |
|------|------|------|------|
| 3.8+ | active | — | — |
| 3.9+ | active | — | — |
| 3.10+ | active | — | — |
| 3.11+ | active | — | — |
| 3.12+ | active | — | — |

## 解决方案

1. **** (85% 成功率)
   ```
   import httpx, asyncio
for delay in (1, 2, 4, 8):
    try:
        async with httpx.AsyncClient() as c:
            r = await c.get(url)
        break
    except httpx.ConnectError:
        await asyncio.sleep(delay)
   ```
2. **** (88% 成功率)
   ```
   transport = httpx.AsyncHTTPTransport(retries=3)
async with httpx.AsyncClient(transport=transport) as c:
    r = await c.get(url)
   ```

## 无效尝试

- **** — Connection refused is immediate; timeouts are irrelevant. (90% 失败率)
- **** — The failure occurs before any HTTP exchange. (85% 失败率)