In the process of finding information, the information on the Internet said. The higher version of pip uses ssl by default, while the pip of python2 does not use ssl;
The local environment is to process the pip of python2 and the pip of python3, and finally there will be an environment called pip2 and pip3
It may be my operation error, which caused the python2 environment to be broken after the directly used pip installation.
How to find it online. Haven't been able to fix the ssl problem of python2
The only way in the end is to do the pip installation again: you must execute python3 and then python2
python3 -m pip install --upgrade pip --force-reinstall
python2 -m pip install --upgrade pip --force-reinstall