Import of Assets failing after update

Following an update from unity 5.2.x to 5.3.1 no assets were populated in the heirarchy and I got these errors:

  • Rebuilding Library because the asset database could not be found!
  • IndexOutOfRangeException: Array index is out of range.
    TCMProcessor.OnPostprocessAllAssets (System.String importedAssets, System.String deletedAssets, System.String movedAssets, System.String movedFromAssetPaths)

What can I do to try and resolve that?

http://forum.unity3d.com/threads/project-hierarchy-removed-after-update.377416/#post-2447570

upon updating the scene had not loaded, even though i selected it from the os explorer