@ptillisch I Should mention, that lots of people, that try the nightly builds are hitting this, with multiple different board types.
Edit: I am hoping that Arduino is not about to release 2.0.5 with this regression. Did not happen on 2.0.4
Work around is to delete the cached cores out of: C:\Users\kurte\AppData\Local\Temp\arduino\cores
Location of temp... will be different from user to user and machine type to machine type (windows, linux, mac)