Trying to open 'Files & images' fails with an error:
[Notice] Trying to get property of non-object
GET /admin/assets/
Line 432 in /Users/macbookbruce/silverstripe/sapphire/filesystem/Folder.php
Its possible this is triggered by replacing/adding images directly into the assets folder instead of going through the CMS but this was OK in 2.2.3.
I'll log a ticket as well