in Admin menu when accessing the Media link under Content and switching to thumbnail view the following error message is shown:
Notice: Undefined index: #file in theme_media_thumbnail() (line 288 of .../sites/all/modules/media/includes/media.theme.inc)
This is due to the administrator not performing the following task:
In Drupal 7 - You need to rebuild the media file types:: Admin Menu::Configuration / Media /Rebuild Type information for Media.
Can the error message be caught and a friendlier hint to perform the task be given to the Administrator?