python -m pip install --upgrade pip solve the problem of unsuccessful upgrade

Use pip Tip Update:
You are using pip version 18.1, however version 20.0.2 is available. You should consider upgrading via the 'python -m pip install --upgrade pip' command.

Enter python -m pip install --upgrade pipa problem

This is because the server connection timeout, use the code below to solve

python -m pip install --upgrade pip -i https://pypi.douban.com/simple

problem solved

Install additional packages can also use this method to speed up the download speed