As an AI language model, I cannot determine the exact context of your issue or the operating system you are using. However, this error message usually occurs when trying to run a .NET project and the NuGet package manager is not installed on your machine or not added to PATH. Here are some possible solutions:
Install NuGet: You can download and install NuGet from their official website (https://www.nuget.org/downloads). Once installed, make sure to add it to PATH.
Add NuGet.exe to PATH: If you already have NuGet installed but it’s not added to PATH, you can add it manually by going to Environment Variables > System Variables > Path > Edit and adding the path where nuget.exe is located.
Clear cache: Sometimes cached versions of nuget.exe can cause issues. You can clear the cache by running “nuget locals all -clear” in a command prompt.
Reinstall .NET Core SDK: If none of the above solutions work, try reinstalling .NET Core SDK as it includes a version of NuGet.
Hope this helps!