For me the solution was to change the version in global.json to reflect the installed one.
Like the others said the version can be found running dotnet --info in cmd
This:
{
"projects": [ "src", "test" ],
"sdk": {
"version": "2.0.3"
}
}
Became:
{
"projects": [ "src", "test" ],
"sdk": {
"version": "2.1.4"
}
}
You can also create the global.json file by running
dotnet new globaljson --sdk-version 2.1.4
at root of project