AVIF, WEBP not supported in renditions preview?

[GarfieldKlon222]

Hi 🙂

I'm generating avif and webp renditions from a jpg original. I can sucessfully create the renditions with the corresponding mime types image/avif or image/webp.

But when I click on the renditions in AEM it shows me this error message:

Preview is not supported for the selected item.

Doesn't AEM support avif and webp in the renditions preview or am I doing something wrong?

[ShivamKumar · Accepted solution]

Hi @GarfieldKlon222 ,

I think this is happening because AEM does not natively preview WebP or AVIF renditions in the Assets UI, even though it supports generating and storing them with correct MIME types. When you click on these renditions, you see the message Preview is not supported for the selected item because the UI JSP (renditions.jsp) does not recognize these formats by default.

        To fix this, overlay /libs/dam/gui/components/admin/renditions/renditions.jsp to /apps/... and update the logic to explicitly allow image/webp and image/avif in the preview condition. This customization enables the AEM UI to render previews for these formats.

[GarfieldKlon222]

Thx, that did the trick. But why does Adobe not allow avif and webp there?

[ShivamKumar]

Hi, Glad it worked.

1. Legacy UI (JSP-based)

• renditions.jsp has hardcoded checks for common MIME types (image/jpeg, image/png, etc.)
• WebP/AVIF are not included in those checks by default.

2. Browser Support Lag

At the time AEM 6.5 and earlier were released:

• WebP: Not supported in all enterprise browsers.
• AVIF: Still very new, minimal adoption.

Adobe avoided enabling previews for formats not universally supported.

3. AEM Cloud Service Still Requires Configuration

• WebP and AVIF are more supported in AEM as a Cloud Service.
• But full Assets UI preview still depends on UI configuration or overlay.