Generating API metadata for Cloud Endpoints, brand new project

Question

So, I've basically created a new project in Android, with nothing but the blank sample activity. I right click the project folder and chose "Add App Engine Backend". I supply it with the key and project number for the project on Google Cloud. When I'm done creating it I'm prompty met with this error.

"There was a problem generating the API metadata for your Cloud Endpoints classes: com.google.api.server.spi.tools.ClientLibGenerator$Language"

Any ideas?

Edit:

Here's what I've tried so far:

1. Delete the project, restart the computer and create it again.

2. Downgrade to Google Plugin 3.8/4.2 for Eclipse from 4.3.

3. Create the project as an App Engine Connected Project.

I get the exact same error every time, wether or not I'm giving out the key and project number. I have no idea of what I'm doing wrong.

Answer 1

Switched from app engine sdk 1.9.4 to 1.9.3 and it worked like a charm.