In the past legacy allowed to create content (folders, articles, images, files) which names contain invisible Unicode characters. Therefore, file paths in DFS database and also in the filesystem are stored with these characters.

After upgrade to eZ Platform, these stored images and files are no longer accessible since FlySystem normalizes paths before loading the file.

https://github.com/thephpleague/flysystem/blob/0.5.12/src/Util.php#L81-#L82

There is a need of migration script which should help to normalize file paths stored in the database as well as file names and directories on the filesystem automatically.