Bug Internal build system error. Backend exited with code 2.

I have several students working their way through Unit 5 of Create with Code and they all have encountered this error. We have tried uninstalling Unity, upgrading Unity, creating a new project, opening past projects known to work, and nothing works. The system always defaults to Safe Mode and list the error: Internal build system error. Backend exited with code 2. We are really in need of help. Thanks.