Error updating indexes using python in google appengine

I'm trying to upload a python sample application onto my own appspot account. It works fine on localhost but whenever I uploads it开发者_如何学运维 via command line/gae launcher, I get this message:

Closing update: new version is ready to start serving.
Uploading index definitions.
Error 400: --- begin server output ---
Building a composite index failed: ApplicationError: 1 
--- end server output ---
Your app was updated, but there was an error updating your indexes. Please retry later    with appcfg.py update_indexes.
2011-05-16 02:45:15 (Process exited with code 0)

The result is that the deployed application cant be seen or has an error. When I run with appcfg.py update_indexes, they tell me index.yaml has errors. I tried to modify it but to no avail..

One of the possible reasons for this is the IAM Roles of the deployer user.

Should be:

• App Engine Deployer - for deployment itself.
• App Engine Service Admin - for splitting traffic and removing old versions.
• Cloud Datastore Index Admin - for updating the indexes.