If you’re an iPhone user, you’ve probably heard of HEIC files. By default, your iPhone saves your photos as this type of file. Adobe and HEIC don’t play well together and you wind up having to convert your HEIC files to JPG.
Read this article if you want to learn how you can convert them on your phone, or change the default file type so that you don’t have to convert them at all.
If you get stuck having to convert them on your PC, try this site.