解决错误：pip is configured with locations that require TLS/SSL,the ssl module in Python is not available。
pip安装包出现错误类似如下：
WARNING: pip is configured with locations that require TLS/SSL, however the ssl module in Python is not available.
Looking in indexes: https://pypi.tuna.tsinghua.edu.cn/simple
Collecting protobuf>=4.25.2 (from -r requirements.txt (line 3))
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/protobuf/
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/protobuf/
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/protobuf/
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/protobuf/
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/protobuf/
Could not fetch URL https://pypi.tuna.tsinghua.edu.cn/simple/protobuf/: There was a problem confirming the ssl certificate: HTTPSConnectionPool(host=‘pypi.tuna.tsinghua.edu.cn’, port=443): Max retries exceeded with url: /simple/protobuf/ (Caused by SSLError(“Can’t connect to HTTPS URL because the SSL module is not available.”)) - skipping
ERROR: Could not find a version that satisfies the requirement protobuf>=4.25.2 (from -r requirements.txt (line 3)) (from versions: none)
ERROR: No matching distribution found for protobuf>=4.25.2 (from -r requirements.txt (line 3))
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.tuna.tsinghua.edu.cn/simple/pip/: There was a problem confirming the ssl certificate: HTTPSConnectionPool(host=‘pypi.tuna.tsinghua.edu.cn’, 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
或者如下错误：
WARNING: pip is configured with locations that require TLS/SSL, however the ssl module in Python is not available.
Collecting protobuf>=4.25.2 (from -r requirements.txt (line 3))
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/protobuf/
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/protobuf/
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/protobuf/
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/protobuf/
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/protobuf/
Could not fetch URL https://pypi.org/simple/protobuf/: There was a problem confirming the ssl certificate: HTTPSConnectionPool(host=‘pypi.org’, port=443): Max retries exceeded with url: /simple/protobuf/ (Caused by SSLError(“Can’t connect to HTTPS URL because the SSL module is not available.”)) - skipping
ERROR: Could not find a version that satisfies the requirement protobuf>=4.25.2 (from -r requirements.txt (line 3)) (from versions: none)
ERROR: No matching distribution found for protobuf>=4.25.2 (from -r requirements.txt (line 3))
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
解决方法：
yum -y install openssl-devel之后重新编译一下Python即可，不需要重新建立软连接。
或者卸载 python之后 重新安装一下。
升级pip：
pip38 install --upgrade pip
