If you are using the “any platform” simulator client (the one that requires running the dotnet command), you will need to update the version of .net core installed on your machine to at least version 2.2 after our updates for the new raid on Jan 22.
You can do this upgrade at any time – all .net core versions are backwards compatible. Just make sure to do it before our next simulator update, which could happen as early as Jan 20 (but might not be until Jan 22, depending on how things go).