The source of the problem

When starting Unity, it displays fail to start Unity Package Manager , and the software environment is Unity 2017.3.0f3.

solution

According to the scheme given on the Internet, I choose the method of adding environment variables

Use the command line to add directly under cmd (note that it is opened in administrator mode), the command is as follows: setx UNITY_NOPROXY localhost,127.0.0.1

In addition, there are methods to modify hosts

Find the C:\Windows\System32\drivers\etc\hosts file, remove the comment symbol before “127.0.0.1 localhost” and save it.