Ubuntu20.04升级Python3.10.5后pip安装报SSL模块不可用错误

• 操作系统：Ubuntu 20.04
• 操作场景：手动升级Python版本至3.10.5后，调用pip执行安装操作时报错，无法完成包安装流程
• 核心报错信息如下：

Defaulting to user installation because normal site-packages is not writeable
WARNING: pip is configured with locations that require TLS/SSL, however the ssl module in Python is not available.
Requirement already satisfied: pip in /usr/local/lib/python3.10/site-packages (22.0.4)
WARNING: Retrying (Retry(total=4, connect=None, read=None, redirect=None, status=None)) after connection broken by 'SSLError("Can't connect to HTTPS URL because the SSL module is not available.")': /simple/pip/
WARNING: Retrying (Retry(total=3, connect=None, read=None, redirect=None, status=None)) after connection broken by 'SSLError("Can't connect to HTTPS URL because the SSL module is not available.")': /simple/pip/
WARNING: Retrying (Retry(total=2, connect=None, read=None, redirect=None, status=None)) after connection broken by 'SSLError("Can't connect to HTTPS URL because the SSL module is not available.")': /simple/pip/
WARNING: Retrying (Retry(total=1, connect=None, read=None, redirect=None, status=None)) after connection broken by 'SSLError("Can't connect to HTTPS URL because the SSL module is not available.")': /simple/pip/
WARNING: Retrying (Retry(total=0, connect=None, read=None, redirect=None, status=None)) after connection broken by 'SSLError("Can't connect to HTTPS URL because the SSL module is not available.")': /simple/pip/
Could not fetch URL https://pypi.org/simple/pip/: There was a problem confirming the ssl certificate: HTTPSConnectionPool(host='pypi.org', port=443): Max retries exceeded with url: /simple/pip/ (Caused by SSLError("Can't connect to HTTPS URL because the SSL module is not available.")) - skipping
WARNING: pip is configured with locations that require TLS/SSL, however the ssl module in Python is not available.
Could not fetch URL https://pypi.org/simple/pip/: There was a problem confirming the ssl certificate: HTTPSConnectionPool(host='pypi.org', port=443): Max retries exceeded with url: /simple/pip/ (Caused by SSLError("Can't connect to HTTPS URL because the SSL module is not available.")) - skipping

• 故障特征：持续提示Python环境ssl模块不可用，多次重试连接PyPI源均因SSLError失败，无法拉取安装资源。

该问题是编译安装Python 3.10.5前未安装OpenSSL开发依赖库，导致编译过程中跳过了ssl模块构建，最终安装的Python运行环境缺少_ssl内置模块。pip默认通过HTTPS协议拉取包资源，依赖ssl模块完成TLS握手，模块缺失时就会触发上述报错。

• 安装Python编译所需的全套依赖，重点包含OpenSSL开发组件
  执行以下命令安装依赖：

  sudo apt update
  sudo apt install -y build-essential zlib1g-dev libncurses5-dev libgdbm-dev libnss3-dev libssl-dev libreadline-dev libffi-dev libsqlite3-dev wget libbz2-dev
  

• 重新编译安装Python 3.10.5
  进入之前存放Python 3.10.5源码的解压目录（如果之前的源码包已经删除，重新解压对应版本的源码包即可），依次执行以下命令完成重新编译安装：

  # 进入源码根目录，根据实际存放路径调整
  cd Python-3.10.5
  # 清理之前的编译缓存，避免旧编译产物干扰
  make clean
  # 配置编译参数，明确启用OpenSSL支持，开启编译优化
  ./configure --enable-optimizations --with-ssl-default-suites=openssl
  # 多线程编译，自动匹配CPU核心数加快编译速度
  make -j$(nproc)
  # 执行altinstall安装，不会覆盖系统默认Python软链接，避免破坏系统依赖
  sudo make altinstall
  

• 验证ssl模块可用性
  编译安装完成后，执行以下命令验证ssl模块是否正常加载：

  python3.10 -c "import ssl; print(ssl.OPENSSL_VERSION)"
  

  命令正常输出OpenSSL版本信息、无模块缺失报错即代表修复成功。
• 验证pip功能
  执行pip升级命令测试功能是否正常：

  python3.10 -m pip install --upgrade pip
  

  无SSLError报错、能正常连接源拉取资源即代表问题完全解决。

• 不要手动修改Ubuntu 20.04系统默认的/usr/bin/python3软链接，系统大量核心组件依赖默认的Python 3.8环境，强行替换会导致apt、桌面组件等功能异常。日常使用新版本Python直接调用python3.10、pip3.10即可。
• 后续编译更高版本Python前，务必先装齐所有开发依赖，避免出现类似模块缺失问题。

内容的提问来源于stack exchange，提问作者AYUSH DHAR UNOFFICIAL