Error on single upload
<You need to select a valid, non-empty file to upload.
Please note: for browser security reasons if you wish to change the image file, you may need to browse and select it again.>
This error currently occurs when the 'File' Attribute is hidden in Admin > Attributes.
You can view hidden attributes by clicking on the 'View hidden attributes' link at the bottom of the page (Admin > Attributes).
Until we fix this in a new release of Asset Bank please make sure that the 'File' attribute is not in this list (click on [show])
After you have 'unhidden' the attribute you will need to [reindex existing items].