On Linux, iPhone HEIC photos need libheif's tools for their previews. Without them, the photos are still backed up and downloadable, and the server says so when it starts.
- Install the decoder for your system: see HEIC photos.
- Restart the service:
systemctl --user restart diune-media-server.
Photos backed up before get their previews in the background, one at a time.
Still no picture?
On Ubuntu 24.04, libheif 1.17.6 fails on some HEIC files from iOS 18 and later. Such a photo keeps its details and shows no picture. libheif 1.18.2 or newer reads them, from the strukturag PPA. The server tries such files again at each start, so after upgrading the decoder, restart the service.