What do you want to deploy? Is it an app to App Engine, as expected here, or maybe Course Builder? If you are trying to deploy Course Builder, you may profit from this
Guide: How to Deploy Course Builder from Any OS.
If you try to deploy an app to App Engine, it is advisable to run gcloud components update first.
What is the output of gcloud info?
More information becomes available if you run: gcloud app deploy --verbosity=debug. What is the output of this command? Prior to posting this information here, you should edit out all private information, such as project names or IDs, user names, and the like, as the information becomes publicly visible.