Quick summary

Imagen couldn't read one or more photos while preparing them for upload. The file name ends in a supported format, but the file's content isn't in a format Imagen can read, or the file is damaged.

How to fix this

1. Look for photos that were renamed, converted or saved by another app. A common example is an iPhone HEIC or a PNG renamed to .jpg. HEIC, PNG, PSD, and GIF aren't supported.
    
2. Try to open the photos in another viewer. If a photo won't open or looks broken, it's damaged. Copy it again from the memory card or original backup.
    
3. Remove or replace the photos that fail, and create the project again.
    
4. Upload the original camera files where you can.