Please perform the upgrade as described in Upgrading the eWallet Server before proceeding below.
The biggest change introduced in 1.2.0 is the removal of the hierarchy system for accounts. The new system is based on a flat approach where every account is equal and each admin users needs to be explicitly added to it. If you've run the migration command shown in the Readme, you should be good to go since your data should have been moved around while the database structure was changed.