# 运行时错误：连接不存在。

- **ID:** `python/starlette-runtimeerror-connection-does-not-exist`
- **领域:** python
- **类别:** runtime_error
- **验证级别:** ai_generated
- **修复率:** 80%

## 根因

尝试使用已经关闭或从未建立的WebSocket连接。

## 版本兼容性

| 版本 | 状态 | 引入 | 弃用 |
|------|------|------|------|
| 3.x | active | — | — |

## 解决方案

1. **Check if WebSocket is connected before using** (85% 成功率)
   ```
   if websocket.client_state == starlette.websockets.WebSocketState.CONNECTED:
    await websocket.send_text('hello')
   ```
2. **Handle disconnection with try-except** (90% 成功率)
   ```
   try:
    await websocket.receive_text()
except RuntimeError:
    # connection closed
    pass
   ```

## 无效尝试

- **Reusing WebSocket object after disconnect** — WebSocket connections are single-use; must accept new connections. (80% 失败率)
- **Assuming connection persists across requests** — Each WebSocket request creates a new connection object. (90% 失败率)