[NextGen Gallery] Invalid data type used for entity. Please use stdClass

Ive updated Photocrati NextGen Gallery to the latest version 2.0.40 and I get this error when trying to create a new gallery and upload any file in it.

Invalid data type used for entity. Please use stdClass or a subclass of C_DataMapper_Model. Arrays will be supported in the future.

I managed to upload the files if i create a Gallery from Manage Galleries – Add new .. then upload from Add Gallery all files I need in the newly created gallery. However the thumnails are all broken, but at least the show in my posts.

Any ideas how to fix this to be able to upload and create new galleries via Add Gallery / Images??