Your Slider {slider.title} works with outdated image relations. Introducing TYPO3 Layersliderlight 5.4.3 the slider uses File Abstraction Layer. In this case, all images must be updated now. Here is a list of images, that would be updated to FAL. Please select at this point a Filemount. At this place the images for this Slider are stored. You can create a new filemount or folder first and come back later. Your slider works in frontend with this version, but keep in mind that you can not edit this slider before you run the update here!