[wp-trac] [WordPress Trac] #64836: Media: skip server image support check when not generating sub-sizes
WordPress Trac
noreply at wordpress.org
Tue Mar 10 16:53:42 UTC 2026
#64836: Media: skip server image support check when not generating sub-sizes
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Reporter: adamsilverstein | Owner: adamsilverstein
Type: defect (bug) | Status: assigned
Priority: normal | Milestone: 7.0
Component: Media | Version: trunk
Severity: normal | Resolution:
Keywords: has-patch | Focuses:
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Description changed by adamsilverstein:
Old description:
> ## Summary
>
> REST API: Skip server-side image editor support check when
> `generate_sub_sizes` is `false`
>
> ## Description
>
> When uploading images via the REST API with `generate_sub_sizes` set to
> `false`, the server still checks whether the image editor supports the
> uploaded image format. This causes uploads of formats like AVIF to fail
> with `rest_upload_image_type_not_supported`, even though the client is
> handling all image processing and the server doesn't need to generate any
> sub-sizes.
>
> The `generate_sub_sizes` parameter was introduced to allow clients (such
> as the block editor with client-side media processing) to handle image
> resizing themselves. When this parameter is `false`, the server-side
> image editor support check is unnecessary and should be skipped.
>
> ### Steps to Reproduce
>
> 1. Enable client-side media processing in the block editor (or use the
> REST API directly with `generate_sub_sizes=false`)
> 2. Attempt to upload an AVIF image on a server where the image editor
> does not support AVIF
> 3. The upload fails with `rest_upload_image_type_not_supported`
>
> ### Expected Result
>
> The upload should succeed because the client is handling all image
> processing.
>
> ### Actual Result
>
> The upload fails with a 400 error: "The web server cannot generate
> responsive image sizes for this image."
>
> ## Proposed Fix
>
> In `WP_REST_Attachments_Controller::create_item_permissions_check()`,
> after the `wp_prevent_unsupported_mime_type_uploads` filter is applied,
> check if `generate_sub_sizes` is explicitly set to `false`. If so, set
> `$prevent_unsupported_uploads` to `false` to bypass the server-side image
> editor support check.
New description:
== Summary
REST API: Skip server-side image editor support check when
`generate_sub_sizes` is `false`
== Description
When uploading images via the REST API with `generate_sub_sizes` set to
`false`, the server still checks whether the image editor supports the
uploaded image format. This causes uploads of formats like AVIF to fail
with `rest_upload_image_type_not_supported`, even though the client is
handling all image processing and the server doesn't need to generate any
sub-sizes.
The `generate_sub_sizes` parameter was introduced to allow clients (such
as the block editor with client-side media processing) to handle image
resizing themselves. When this parameter is `false`, the server-side image
editor support check is unnecessary and should be skipped.
=== Steps to Reproduce
1. Enable client-side media processing in the block editor (or use the
REST API directly with `generate_sub_sizes=false`)
2. Attempt to upload an AVIF image on a server where the image editor does
not support AVIF
3. The upload fails with `rest_upload_image_type_not_supported`
=== Expected Result
The upload should succeed because the client is handling all image
processing.
=== Actual Result
The upload fails with a 400 error: "The web server cannot generate
responsive image sizes for this image."
== Proposed Fix
In `WP_REST_Attachments_Controller::create_item_permissions_check()`,
after the `wp_prevent_unsupported_mime_type_uploads` filter is applied,
check if `generate_sub_sizes` is explicitly set to `false`. If so, set
`$prevent_unsupported_uploads` to `false` to bypass the server-side image
editor support check.
--
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Ticket URL: <https://core.trac.wordpress.org/ticket/64836#comment:1>
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