# 错误：忽略已安装的发行版，因为它安装在非用户位置

- **ID:** `python/pip-install-ignore-installed`
- **领域:** python
- **类别:** install_error
- **验证级别:** ai_generated
- **修复率:** 80%

## 根因

Pip 检测到包安装在系统目录中，拒绝在没有 --user 或 --upgrade 标志的情况下覆盖它。

## 版本兼容性

| 版本 | 状态 | 引入 | 弃用 |
|------|------|------|------|
| 3.8 | active | — | — |
| 3.9 | active | — | — |
| 3.10 | active | — | — |

## 解决方案

1. **Install with --user flag** (90% 成功率)
   ```
   pip install --user package_name
   ```
2. **Use a virtual environment** (95% 成功率)
   ```
   python -m venv myenv && source myenv/bin/activate && pip install package_name
   ```

## 无效尝试

- **Forcing reinstall with --force-reinstall** — May still conflict with system permissions. (50% 失败率)
- **Deleting the system package manually** — Risky and may break system dependencies. (70% 失败率)