Systems and methods are disclosed for a single sign-on (SSO) enterprise system with multiple data centers that use a lightweight cookie on a user's client device. The lightweight cookie includes a reference to a data center in which the user is already authenticated, and a new data center contacts the old data center for creating a session for the user on the new data center. If the old data center is unavailable, then the new data center may fall back to accessing a local security store, a backup of keys, security tokens, and/or other security data, in order to create a local session for the user on the new data center.