Nuget can't find the package problem

After VS2019 is installed, the problem that the project's Nuget cannot find the package is handled:

After reinstalling the system, I found that when the newly installed VS2019 used Nuget to search for the SDK, it kept prompting that the package could not be found;

Solution:

1. Click the settings button on the right,

2. Select "Package Source" in the tree structure on the left side of the pop-up window, and then click the Add button at the top right:

Enter the following information: https://api.nuget.org/v3/index.json nuget.org

3. After confirming, it will return to the Nuget main page. At this time, we will select the package source in the upper right as "all" or the newly added "nuget.org", and search again to find what we need.SDK too.

After cloning, for new projects, you need to restore the nuget package