Then follow the steps
- Close the project and rename the project.json file and reopen and check if its resolved
- Go to .Nuget folder (
Location:C:\Users\<Username>\.nuget\Packages
) and rename the packages folder and then reopen the project and check if the issue persists
If the issue is still there create a new project and check if the issue there in that project also, If yes then try downgrading the packages to older stable versions like 22.x
cheers