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. 

Any thoughts?
['https://Stackoverflow.com/questions/52653776', 'https://Stackoverflow.com', 'https://Stackoverflow.com/users/10458445/']
It looks like there's [an active issue on Google's issue tracker](https://issuetracker.google.com/117145272) (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.

**UPDATE (OCT 9, 2018):** Cloud SDK version 220.0.0, which fixes the dev\_appserver.py issue, is now available. I updated (via `gcloud components update`) and verified that it works. (Note: there are already a couple of complaints on the Issue Tracker that dev\_appserver.py takes too long to load now. I didn't notice a significant difference from version 218, but I didn't compare timings.)
On Windows, `dev_appserver.py %CD%` is enough if your .yaml file has the default `app.yaml` name. Otherwise `dev_appserver.py %CD%/your-file-name.yaml`