SD card in Finder no longer reads, appears as generic document icon
Many Macs have a built-in SD-card reader or a USB-SD card reader attached to read the SD-card that is used on many digital cameras. In prior operating systems some would appear as one of these two icons:
Under Mojave, we have not been able to reproduce this behavior, requiring extra steps to import data off the SD card
into the Mac. Now we get a generic icon, such as is shown in this image, and a dialog saying Untitled can't be opened (Untitled being the icon under the Macintosh HD on the left sidebar):
When this happens, Go to the Go menu -> Applications and open Image Capture to load the card.
Image Capture will let you select and drag out photos to the Finder that you want to use. Create a folder a folder on the desktop to drag these photos out to.
This happened with a recently upgraded to Mojave Early 2015 MacBook Pro 13" reading an SD card formatted for a Panasonic Lumix FZ80. Not all camera cards are formatted the same way, just remember Image Capture will usually work when the Finder does not.