I've been successfully running the local development server daily and have made no changes except that I called "gcloud components update" just before it stopped working. Now I get:
..snip... <<PATH TO MY SDK>>/google-cloud-sdk/platform/google_appengine/google/appengine/tools/devappserver2/application_configuration.py", line 518, in _parse_configuration with open(configuration_path) as f: IOError: [Errno 2] No such file or directory: 'app.yaml'
Of course app.yaml hasn't moved.
It looks like there's an active issue on Google's issue tracker (opened on Oct 2, 2018) pertaining to this:
After updating to the Python (2.7) extensions for GAE to version 1.9.76, I am no longer able to run my code with dev_appserver.py
As of Oct 3, a fix appears to be in the works, but for now they suggest downgrading Google Cloud SDK to version 218.0.0:
It seems like you are affected by a known issue regarding ‘dev_appserver.py’ breaks in Google Cloud SDK version [219.0.1]. App Engine specialists are currently working to resolve it. However there is no ETA at this moment. As a workaround you can downgrade the Google Cloud SDK version using this command:
gcloud components update --version 218.0.0
The assignee of the issue will post an update on that issue when it has been resolved.