An iPhone photo that won't open is usually a HEIC file (ending in .heic). Convert it to JPG, or set the camera to Most Compatible so it shoots JPG.
What HEIC is
HEIC (High Efficiency Image Container) has been the iPhone default since 2017. It uses HEVC compression, also found in 4K video, and stores photos at about half the size of JPG, with support for burst photos, Live Photos and wide color. Windows may need an extra codec, older Android devices may not open it, and many upload forms reject it.
Convert a HEIC file to JPG
Drop the HEIC file into the image format converter, choose JPG (or PNG for graphics), and download. It runs on your device, so IDs and leases are not uploaded. Keep the original HEIC as the master copy, since conversion re-encodes the image.
Change the iPhone camera format
- Open Settings → Camera → Formats.
- Switch from High Efficiency to Most Compatible.
New photos are JPG and use about twice the storage. To stay on High Efficiency, enable Settings → Photos → Transfer to Mac or PC → Automatic for cable transfers.
Sharing from Apple apps
Some Apple apps convert HEIC to JPG when sharing. Email attachments, cloud-drive uploads and file copies may keep HEIC, which is why a photo can work in Messages and fail on an upload form.
Should you convert your whole library?
No. JPG takes substantially more storage. Keep HEIC originals and convert photos as needed. The image format guide covers WebP, PNG and AVIF.