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Fix: #57469 fatal error when a sidebar widgets set to null #9603

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Fix: #57469 fatal error when a sidebar widgets set to null #9603

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474077d
fix: replace null sidebar widget entries with empty arrays
DarkMatter-999 Aug 26, 2025
fff3b1e
docs: improve clarity of inline comments
DarkMatter-999 Aug 27, 2025
e5d56b5
test: add tests for null sidebar normalization in `retrieve_widgets()…
DarkMatter-999 Aug 29, 2025
1c298fd
fix: add check for whether the value is an array
DarkMatter-999 Sep 9, 2025
ce06687
docs: update comments to reflect changes
DarkMatter-999 Sep 9, 2025
484c479
test: simplified widget tests
DarkMatter-999 Sep 12, 2025
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14 changes: 14 additions & 0 deletions src/wp-includes/widgets.php
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Original file line number Diff line number Diff line change
Expand Up @@ -1350,6 +1350,13 @@ function retrieve_widgets( $theme_changed = false ) {
$sidebars_widgets = _wp_remove_unregistered_widgets( $sidebars_widgets, $registered_widgets_ids );
$sidebars_widgets = wp_map_sidebars_widgets( $sidebars_widgets );

// Replace null values inside the array with an empty array.
foreach ( $sidebars_widgets as $key => $value ) {
if ( null === $value ) {
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@westonruter westonruter Sep 8, 2025

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What if it was set to something other than an array or null, like a string, boolean, integer, or object? Wouldn't this be more appropriate:

Suggested change
if ( null === $value ) {
if ( ! is_array( $value ) ) {

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@DarkMatter-999 DarkMatter-999 Sep 9, 2025

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moving forward with this approach

$sidebars_widgets[ $key ] = array();
}
}
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@westonruter westonruter Sep 8, 2025

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Alternatively:

Suggested change
// Replace null values inside the array with an empty array.
foreach ( $sidebars_widgets as $key => $value ) {
if ( null === $value ) {
$sidebars_widgets[ $key ] = array();
}
}
$sidebars_widgets = array_filter( $sidebars_widgets, 'is_array' );

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@DarkMatter-999 DarkMatter-999 Sep 9, 2025

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I think checking for is_array will be a better solution and is a drop in replacement because it preserves sidebar keys and guarantees any downstream operations receive arrays, this is consistent with how older PHP version like 7.4 handle array_merge and array_search.

Using array_filter($sidebars_widgets, 'is_array') will remove entries that are not arrays, which can drop keys and change control flow in the downstream code that expects those keys to exist.


// Find hidden/lost multi-widget instances.
$shown_widgets = array_merge( ...array_values( $sidebars_widgets ) );
$lost_widgets = array_diff( $registered_widgets_ids, $shown_widgets );
Expand Down Expand Up @@ -1511,6 +1518,13 @@ function wp_map_sidebars_widgets( $existing_sidebars_widgets ) {

$old_sidebars_widgets = _wp_remove_unregistered_widgets( $old_sidebars_widgets );

// Replace null values inside the array with an empty array.
foreach ( $new_sidebars_widgets as $key => $value ) {
if ( null === $value ) {
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@westonruter westonruter Sep 8, 2025

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Suggested change
if ( null === $value ) {
if ( ! is_array( $value ) ) {

$new_sidebars_widgets[ $key ] = array();
}
}
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@westonruter westonruter Sep 8, 2025

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Alternatively:

Suggested change
// Replace null values inside the array with an empty array.
foreach ( $new_sidebars_widgets as $key => $value ) {
if ( null === $value ) {
$new_sidebars_widgets[ $key ] = array();
}
}
$new_sidebars_widgets = array_filter( $new_sidebars_widgets, 'is_array' );


if ( ! empty( $old_sidebars_widgets ) ) {

// Go through each remaining sidebar...
Expand Down
55 changes: 55 additions & 0 deletions tests/phpunit/tests/widgets.php
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Original file line number Diff line number Diff line change
Expand Up @@ -1359,4 +1359,59 @@ public function test_sidebar_guessing_one_menu_per_sidebar() {
);
$this->assertSameSetsWithIndex( $expected_sidebars, $new_next_theme_sidebars );
}

/**
* Ensures null sidebar values are converted to empty arrays in retrieve_widgets().
*
* @covers ::retrieve_widgets
* @ticket 57469
*/
public function test_retrieve_widgets_converts_null_sidebar_to_empty_array() {
global $sidebars_widgets;
wp_widgets_init();
$this->register_sidebars( array( 'primary', 'secondary', 'wp_inactive_widgets' ) );

$sidebars_widgets = array(
'primary' => null,
'secondary' => array( 'text-1' ),
'extra_sidebar' => array( 'unregistered_widget-1' ),
'wp_inactive_widgets' => array(),
);

$result = retrieve_widgets( true );
$this->assertArrayHasKey( 'primary', $result );
$this->assertIsArray( $result['primary'], 'Primary sidebar should be an array after normalization.' );
$this->assertEmpty( $result['primary'], 'Primary sidebar should be an empty array when original value was null.' );
$this->assertArrayNotHasKey( 'extra_sidebar', $result, 'Unregistered sidebar should be removed.' );
}

/**
* Ensures wp_map_sidebars_widgets() normalizes null sidebar widget arrays.
*
* @covers ::wp_map_sidebars_widgets
* @ticket 57469
*/
public function test_wp_map_sidebars_widgets_converts_null_sidebar_to_empty_array() {
$this->register_sidebars( array( 'primary', 'wp_inactive_widgets' ) );
// Theme data containing a null so the normalization loop runs.
set_theme_mod(
'sidebars_widgets',
array(
'time' => time(),
'data' => array(
'primary' => null,
),
)
);

$prev_theme_sidebars = array(
'primary' => null,
'wp_inactive_widgets' => array(),
);

$new_sidebars = wp_map_sidebars_widgets( $prev_theme_sidebars );
$this->assertArrayHasKey( 'primary', $new_sidebars );
$this->assertIsArray( $new_sidebars['primary'], 'Primary sidebar should be an array after normalization.' );
$this->assertEmpty( $new_sidebars['primary'], 'Primary sidebar should be an empty array when original value was null.' );
}
}
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