pymongo.errors.OperationFailure: command SON([('authenticate', 1), ('user', u'root'), ('nonce', u''), ('key', u'')]) failed: auth failed
Steps to solve:
If using global pymongo, update it.
sudo pip install pymongo --upgrade
If using pymongo from lib folder
Fix the version in requirements.txt, as of today, latest version is 3.0.3, you can check it out from here.
Upgrade the packages:
sudo pip install -r requirements.txt -t lib/ --upgrade
Redeploy. This will hopefully fix your heroku and Google App Engine deployment with pymongo.