Cover: Avoid passing null as the featured image size by t-hamano · Pull Request #81444 · WordPress/gutenberg

t-hamano · 2026-08-11T15:29:40Z

What?

The Cover block asks WordPress for the featured image using null as the image size. This PR passes 'full' instead, which is what the code already ends up using anyway.

This fixes the PHP 8.5 CI failures on trunk.

Why?

Passing null as an image size was never valid — get_the_post_thumbnail_url() expects a size name or a width/height array.

PHP 8.5 now deprecates using null as an array key, and a recent WordPress change — r63177 — made image_constrain_size_for_editor() do exactly that kind of lookup with whatever size it is handed. The previous code never reached the lookup; the new one does. So our invalid null started producing a deprecation notice, which PHPUnit reports as a test error:

Tests_Blocks_Render_Cover::test_gutenberg_render_block_core_cover
Using null as an array offset is deprecated, use an empty string instead

Whatever Core decides to do about r63177, passing null here is our bug, so this is worth fixing on its own.

How?

'full' was chosen over 'post-thumbnail' because it keeps the output identical — passing null today always resolves to the full-size image URL, and 'full' does the same.

The <img> branch just above already uses 'post-thumbnail' and is intentionally left alone — that one is a responsive image, not a CSS background.

Testing Instructions

The failing test Tests_Blocks_Render_Cover::test_gutenberg_render_block_core_cover already covers this path, so green CI is the main check.

To confirm nothing changed visually:

Set a featured image on a post.
Add a Cover block, enable Use featured image, and turn on Fixed background or Repeated background.
Leave the image size unset in the sidebar.
On the front end, inspect the background-image URL on .wp-block-cover__image-background. It should be the full-size image, the same as before this change.

Use of AI Tools

Claude Code was used to track down the cause of the CI failure and to draft this description. The one-line change and the choice of 'full' were reviewed and accepted by me.

The parallax/repeated branch passed `null` to `get_the_post_thumbnail_url()` when the `sizeSlug` attribute is absent, explicitly defeating the function's own `'post-thumbnail'` default. `$size` is documented as `string|int[]`, so `null` was never a valid value. `null` propagates down to `image_constrain_size_for_editor()`, which since WordPress r63177 evaluates `$_wp_additional_image_sizes[ $size ]` through `isset()`. On PHP 8.5 a null array offset is deprecated, which surfaces the latent bug as a test error. Use `'full'` rather than `'post-thumbnail'` so the rendered output is unchanged: `image_get_intermediate_size()` bails out early on a falsy `$size`, so the current code always resolves to the full-size URL. Co-Authored-By: Claude <noreply@anthropic.com>

Co-Authored-By: Claude <noreply@anthropic.com>

aduth

Would be good to have some test coverage here if we could, but given that this is blocking everything in trunk it's better to get a fix in place.

aduth · 2026-08-11T15:45:31Z

Would be good to have some test coverage here if we could,

Reconciling this with the claim in the PR description:

The failing test Tests_Blocks_Render_Cover::test_gutenberg_render_block_core_cover already covers this path, so green CI is the main check.

I guess this is true and validates the decision to use 'full', as we assert it explicitly:

gutenberg/phpunit/blocks/render-block-cover-test.php

Line 82 in 121e579

    
           $this->assertStringContainsString( wp_get_attachment_image_url( self::$attachment_id, 'full' ), $rendered );

It could be further improved with tests around sizeSlug existence which currently has no coverage, but not a blocker.

t-hamano · 2026-08-11T15:48:24Z

Thanks for the review!

This PR appears to be valid, as the unit tests are passing on PHP 8.5.
https://github.com/WordPress/gutenberg/actions/runs/31507399760/job/93833160761?pr=81444

github-actions · 2026-08-11T15:49:47Z

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Co-authored-by: t-hamano <wildworks@git.wordpress.org>
Co-authored-by: aduth <aduth@git.wordpress.org>

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t-hamano · 2026-08-11T16:03:56Z

I investigated the AI's analysis results.

Ideally, for consistency with the get_the_post_thumbnail line, the fallback size for get_the_post_thumbnail_url should be post-thumbnail. However, since null has effectively resolved to the full size until now, changing it to post-thumbnail might unintentionally reduce image resolution. For backward compatibility, it would be best to specify full for now.

t-hamano · 2026-08-11T16:21:23Z

This PR needs to be backported because the same CI error is occurring on the wp/7.1 branch.

* Cover: Avoid passing null as the featured image size The parallax/repeated branch passed `null` to `get_the_post_thumbnail_url()` when the `sizeSlug` attribute is absent, explicitly defeating the function's own `'post-thumbnail'` default. `$size` is documented as `string|int[]`, so `null` was never a valid value. `null` propagates down to `image_constrain_size_for_editor()`, which since WordPress r63177 evaluates `$_wp_additional_image_sizes[ $size ]` through `isset()`. On PHP 8.5 a null array offset is deprecated, which surfaces the latent bug as a test error. Use `'full'` rather than `'post-thumbnail'` so the rendered output is unchanged: `image_get_intermediate_size()` bails out early on a falsy `$size`, so the current code always resolves to the full-size URL. Co-Authored-By: Claude <noreply@anthropic.com> * Cover: Add CHANGELOG entry Co-Authored-By: Claude <noreply@anthropic.com> --------- Co-authored-by: t-hamano <wildworks@git.wordpress.org> Co-authored-by: aduth <aduth@git.wordpress.org>

github-actions · 2026-08-11T16:42:52Z

I just cherry-picked this PR to the wp/7.1 branch to get it included in the next release: cdc13e2

This updates the pinned commit hash of the Gutenberg repository from `ea285b45692aed6c4f95353671393402f97f0aa7` to `b9743a015526ac8fd79298fd4e96cf002cee333b`. A full list of changes included in this commit can be found on GitHub: WordPress/gutenberg@ea285b4...b9743a0 - Style states: fix state deselection when selecting the already selected block (WordPress/gutenberg#81277) - Global styles: render element styles set only inside a breakpoint (WordPress/gutenberg#81265) - Style states: Fix phantom pseudo element style output (WordPress/gutenberg#81291) - Docs: remove breakpoint-only element style example from global styles guide (WordPress/gutenberg#81308) - theme.json schema: responsive states belong to blocks (WordPress/gutenberg#81253) - theme.json schema: allow responsive states on block style variations (WordPress/gutenberg#81309) - Render viewport state element styles in the editor (WordPress/gutenberg#81307) (WordPress/gutenberg#81311) - Site Editor: Decode HTML entities in Identity fields (WordPress/gutenberg#81269) (WordPress/gutenberg#81320) - Editor: Keep the canvas height stable while resizing the canvas (WordPress/gutenberg#81374) - Playlist: Normalize Waveform Player configuration handling (WordPress/gutenberg#81375) - Playlist: Improve audio conversion and track selection (WordPress/gutenberg#80926) (WordPress/gutenberg#81385) - fix: order site identity changes predictably (WordPress/gutenberg#81283) - Cover: Avoid passing null as the featured image size (WordPress/gutenberg#81444) - components/Menu: Restore Modal focus return when menu items close (WordPress/gutenberg#81446) - Notes: Fix text wrapping for long usernames in collaboration sidebar (WordPress/gutenberg#81406) - Site Editor: Use inverted ThemeProvider seed for portaled UI (WordPress/gutenberg#81296) Props wildworks. See #65529. git-svn-id: https://develop.svn.wordpress.org/branches/7.1@63209 602fd350-edb4-49c9-b593-d223f7449a82

* Cover: Avoid passing null as the featured image size The parallax/repeated branch passed `null` to `get_the_post_thumbnail_url()` when the `sizeSlug` attribute is absent, explicitly defeating the function's own `'post-thumbnail'` default. `$size` is documented as `string|int[]`, so `null` was never a valid value. `null` propagates down to `image_constrain_size_for_editor()`, which since WordPress r63177 evaluates `$_wp_additional_image_sizes[ $size ]` through `isset()`. On PHP 8.5 a null array offset is deprecated, which surfaces the latent bug as a test error. Use `'full'` rather than `'post-thumbnail'` so the rendered output is unchanged: `image_get_intermediate_size()` bails out early on a falsy `$size`, so the current code always resolves to the full-size URL. Co-Authored-By: Claude <noreply@anthropic.com> * Cover: Add CHANGELOG entry Co-Authored-By: Claude <noreply@anthropic.com> --------- Co-authored-by: t-hamano <wildworks@git.wordpress.org> Co-authored-by: aduth <aduth@git.wordpress.org>

This updates the pinned commit hash of the Gutenberg repository from `ea285b45692aed6c4f95353671393402f97f0aa7` to `b9743a015526ac8fd79298fd4e96cf002cee333b`. A full list of changes included in this commit can be found on GitHub: WordPress/gutenberg@ea285b4...b9743a0 - Style states: fix state deselection when selecting the already selected block (WordPress/gutenberg#81277) - Global styles: render element styles set only inside a breakpoint (WordPress/gutenberg#81265) - Style states: Fix phantom pseudo element style output (WordPress/gutenberg#81291) - Docs: remove breakpoint-only element style example from global styles guide (WordPress/gutenberg#81308) - theme.json schema: responsive states belong to blocks (WordPress/gutenberg#81253) - theme.json schema: allow responsive states on block style variations (WordPress/gutenberg#81309) - Render viewport state element styles in the editor (WordPress/gutenberg#81307) (WordPress/gutenberg#81311) - Site Editor: Decode HTML entities in Identity fields (WordPress/gutenberg#81269) (WordPress/gutenberg#81320) - Editor: Keep the canvas height stable while resizing the canvas (WordPress/gutenberg#81374) - Playlist: Normalize Waveform Player configuration handling (WordPress/gutenberg#81375) - Playlist: Improve audio conversion and track selection (WordPress/gutenberg#80926) (WordPress/gutenberg#81385) - fix: order site identity changes predictably (WordPress/gutenberg#81283) - Cover: Avoid passing null as the featured image size (WordPress/gutenberg#81444) - components/Menu: Restore Modal focus return when menu items close (WordPress/gutenberg#81446) - Notes: Fix text wrapping for long usernames in collaboration sidebar (WordPress/gutenberg#81406) - Site Editor: Use inverted ThemeProvider seed for portaled UI (WordPress/gutenberg#81296) Props wildworks. See #65529. Built from https://develop.svn.wordpress.org/branches/7.1@63209 git-svn-id: http://core.svn.wordpress.org/branches/7.1@62402 1a063a9b-81f0-0310-95a4-ce76da25c4cd

github-actions Bot added the [Package] Block library /packages/block-library label Aug 11, 2026

Cover: Add CHANGELOG entry

2dcdaab

Co-Authored-By: Claude <noreply@anthropic.com>

t-hamano added [Type] Code Quality Issues or PRs that relate to code quality [Block] Cover Affects the Cover Block - used to display content laid over a background image labels Aug 11, 2026

aduth approved these changes Aug 11, 2026

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t-hamano marked this pull request as ready for review August 11, 2026 15:49

t-hamano requested review from ajitbohra and fabiankaegy as code owners August 11, 2026 15:49

t-hamano added the Backport to WP 7.1 Beta/RC Pull request that needs to be backported to the WordPress major release that's currently in beta label Aug 11, 2026

t-hamano mentioned this pull request Aug 11, 2026

Site Editor: Use inverted ThemeProvider seed for portaled UI #81296

Merged

aduth mentioned this pull request Aug 11, 2026

Env: Update git to latest commit when --update passed #81447

Merged

t-hamano merged commit ab730b2 into trunk Aug 11, 2026
60 checks passed

t-hamano deleted the fix/cover-featured-image-null-size branch August 11, 2026 16:40

github-actions Bot added this to the Gutenberg 23.8 milestone Aug 11, 2026

github-actions Bot removed the Backport to WP 7.1 Beta/RC Pull request that needs to be backported to the WordPress major release that's currently in beta label Aug 11, 2026

github-actions Bot added the Backported to WP Core Pull request that has been successfully merged into WP Core label Aug 11, 2026

t-hamano mentioned this pull request Aug 12, 2026

General: Bump the pinned hash for Gutenberg to b9743a WordPress/wordpress-develop#13015

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mukeshpanchal27 mentioned this pull request Aug 13, 2026

Media: Guard the image size lookup in image_constrain_size_for_editor() WordPress/wordpress-develop#13032

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Cover: Avoid passing null as the featured image size - #81444

Cover: Avoid passing null as the featured image size#81444
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How?

Testing Instructions

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t-hamano commented Aug 11, 2026 •

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