The program '[13492] dotnet.exe' has exited with code -2147450749

This could happen if you don't have the correct framework installed. Go to https://aka.ms/dotnet-download to get the latest framework.

I did have a global.json as @Lex Li and @DavidG proposed. The problem was some leftover bits from RC2. I uninstalled all core components, reinstalled, and rebooted. After that things worked again. Thanks everyone for your other solutions !