# 错误：找不到满足 somepkg>=2.0.0b1 要求的版本（可用版本：1.9.0, 1.9.1）
错误：找不到与 somepkg>=2.0.0b1 匹配的分发包

- **ID:** `python/pip-pre-release-not-installed`
- **领域:** python
- **类别:** install_error
- **验证级别:** ai_generated
- **修复率:** 80%

## 根因

pip 默认排除预发布版本，因此即使索引上存在预发布版本，`>=2.0.0b1` 也不会匹配。

## 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. **** (95% 成功率)
   ```
   pip install --pre 'somepkg>=2.0.0b1'
   ```
2. **** (90% 成功率)
   ```
   pip install 'somepkg==2.0.0b1'
   ```

## 无效尝试

- **** — Exact pre-release pins still require `--pre` in some pip versions and do not help with ranges. (60% 失败率)
- **** — Trusted-host affects TLS, not version filtering. (95% 失败率)
- **** — Pre-release filtering is deterministic. (98% 失败率)