NeedIndexError At Google App Engine Forever

I deployed and ran my app at GAE a few hours ago. It still fails because it needs to order certain datastore item, and the index needed for that is still not generated by GAE. So a

Solution 1:

FWIW, in some cases (multi-module apps for example) the plain appcfg.py update used to deploy the app code might not update the index.yaml file.

Try specifically updating the index using appcfg.py update_indexes - you should be able to see the index info in the Developer Console right away (it may still take a while for indexing to be performed and become effective).