Last updated: August 29, 2026

My HEIC files are greyed out

A greyed-out HEIC file in an upload window isn't corruption or a broken file, it's the website's own accept attribute telling your browser which file types the form will take, and HEIC isn't on that list. The file opens fine everywhere else; the dimming only exists inside that one upload dialog, on that one site.

Why is the file picker filtering by file type?

Websites control this with one HTML attribute, accept, set on the file input element behind the upload button. The HTML specification defines accept as a filter for what file types the file selector should suggest, and in practice that means the operating system's own file picker dims or hides anything that doesn't match. If a site's accept list is set to image/jpeg and image/png, a HEIC file shows up in the same folder, visible, but not clickable, because the browser is honoring exactly what the site's code told it to show.

This isn't a quirk of an old or unusual browser, either. Browser support for the accept attribute is effectively universal at this point, per caniuse.com's own tracking, which means the greyed-out behavior shows up the same way in Chrome, Firefox, Edge and Safari alike. Updating a browser, or switching to a different one, doesn't change what a specific site's form allows; the filter lives in that site's code, not in the browser you happen to be using.

Why this isn't file corruption

It's tempting to assume a greyed-out file is damaged, especially if it was just downloaded, AirDropped, or copied from a phone. It isn't. The same HEIC file that's unselectable in this one upload window opens normally in every viewer, editor, and other upload form on the same PC, proof the file itself is intact. What changed is which form you're looking at, not the file. If a HEIC file genuinely won't open anywhere at all, that's a different, unrelated problem, worth checking against how to open HEIC files generally rather than this page.

A quick way to confirm the file is fine: open it in Windows Photos, Preview on a Mac, or any other viewer already on the device. If it opens and displays correctly there, the file is intact and the problem is entirely specific to this one upload form's filter, not the photo, the camera that took it, or however it arrived on this computer.

The "show all files" workaround, and its real limit

Most file pickers offer a way around the filter: a dropdown near the bottom of the dialog, often labeled something like Custom Files or Files of type on Windows, that can be switched to All Files, revealing every file including the greyed-out ones. MDN's own documentation confirms this directly: in most cases, users can toggle an option in the file chooser to override the filter and select any file. The catch is that switching it off doesn't change what the server accepts. The site's accept attribute was only ever a hint to the browser's picker; the same documentation is explicit that it should be validated server-side, not relied on as a validation tool. Overriding the filter to select a HEIC file usually just moves the rejection one step later, to an error after upload instead of a dimmed file before it.

There's one genuine gap in the filter, too, confirmed in the HTML standard's own issue tracker: the accept attribute only governs the picker dialog, not drag-and-drop. Dragging a HEIC file directly onto an upload zone can bypass the greyed-out filter entirely, since browsers don't currently apply accept to dropped files the same way they apply it to the picker. That doesn't mean the upload will succeed, the server-side check above still applies either way, it just means the greyed-out picker and a drag-and-drop zone on the same page can behave differently for the identical file.

The actual fix: convert the format

Since the filter reflects a real limit on what the site processes, not a bug to route around, the fix is changing the file rather than out-maneuvering the picker. Converting HEIC to JPG in your browser produces a file the accept attribute already allows, so it shows up selectable, not greyed out, the moment the upload dialog opens again. This is also the same fix that applies when a form rejects HEIC outright instead of greying it out; see why upload forms reject HEIC for that related, more common version of the same underlying problem.

If an entire folder of photos shows up greyed out at once, rather than a single file, that usually means every photo in it came from the same HEIC-producing source, an iPhone import or a cloud backup set to keep originals, and the whole batch needs the same conversion. The HEIC converter hub covers every output format this site handles beyond JPG, useful if the destination form wants PNG or PDF instead.

One honest limit worth stating: converting fixes the file, not the form's design. If a site's upload widget has other unrelated problems, a low file-size cap, a broken picker on a specific browser, those don't go away just because the format now matches. Converting to JPG removes exactly one obstacle, the format check, which happens to be the one causing the greyed-out files in the first place.

Windows vs macOS, honestly compared

Both operating systems dim non-matching files by default, under the same browser-level filter; MDN describes this as true of most operating systems generally, not one specifically. Where they differ in practice is the override: Windows file pickers typically show an explicit file-type dropdown near the bottom that can be switched to All Files. On macOS the override exists too, though its exact label and behavior vary more by browser than by the operating system itself. Neither difference changes the outcome described above: seeing more files in the picker doesn't make the server accept them. For background on the format both platforms are filtering out, see what HEIC actually is and how it compares to JPEG.

Mobile browsers add a third variable on top of the OS difference: an iPhone or Android photo picker often shows its own gallery view rather than a traditional file browser, and that view can apply the accept filter differently again, sometimes hiding non-matching photos from the grid entirely rather than dimming them. The underlying cause is identical either way, the form's accept attribute doesn't list HEIC, only the visual presentation of "filtered out" changes depending on which picker UI happens to be rendering it.

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