Deprecated: Creation of Dynamic Property

Why it happens

• A plugin or theme assigns a value to a property its class never declared, such as $this->items = array(); in a class with no public $items;. PHP 8.2 made that deprecated.
• The host moved the site from PHP 8.1 or older to PHP 8.2 or newer. The code did not change, but PHP now reports it.
• The author never updated the plugin or theme for PHP 8.2. The message names the file, so the path shows whose code it is.
• WP_DEBUG is on and WordPress shows errors on the page (WP_DEBUG_DISPLAY is on, which is the default), so a message that is normally hidden reaches visitors.

How to fix it

Try the fixes in this order. Each one is independent: stop as soon as the error is gone.

The message means that some code gave a value to a property its class never declared. PHP 8.2 started reporting that as a deprecation. It is not a warning and not a fatal error: the code runs, the property is created, and the page loads. The path in the message names the plugin or theme that wrote the code, and the fix belongs to its author. Update or replace it. You can keep visitors from seeing the message by writing errors to a log instead of the page.

What you see#

The message is plain text with no styling. PHP prints it where the code runs, so it can land at the bottom of a page, above the admin menu, or in the middle of a layout.

I made it with a one-file plugin:

<?php/*Plugin Name: My Plugin*/class MyPlugin {	public function __construct() {		$this->items = array( 1, 2, 3 );	}}add_action( 'wp_footer', function () {	$p = new MyPlugin();	echo 'Items: ' . count( $p->items );} );

The class has no $items declared. PHP creates it on the spot, and PHP 8.2 and newer say so.

How it works#

Before PHP 8.2, you could assign to any property name on any object, and PHP made it. A typo in a name created a new property and hid the bug. PHP 8.2 made this deprecated, unless the class opts in. PHP's RFC says PHP 9.0 will throw an Error instead, so the message is a notice that the code will break later.

I ran the same file on four PHP versions. The only version difference was 8.2:

PHP reports it when the property is created, which is once per object and not once per assignment. In my test, two objects of the same class gave two messages, and assigning the property a second time on one object gave none.

What PHP does not flag#

I tried each case below on PHP 8.3. Only the first is flagged.

Reading a property that was never created is a different message: Warning: Undefined property: Declared::$nope. This page is about creating one. For the array version of the same idea, see the undefined array key page.

WordPress core marks its own classes the same way. WordPress 7.1.4 carries #[AllowDynamicProperties] 131 times, in 130 files, such as WP_Comment and WP_List_Table. That is why a clean install is silent and why the message almost always names a plugin or theme.

Why you may see it only sometimes#

PHP raises the message. Whether it reaches the page depends on WordPress. In wp_debug_mode(), WP_DEBUG off sets error_reporting to a list that leaves out E_DEPRECATED. So on most live sites the message is dropped before it is shown or logged. It shows up when WP_DEBUG is on. I tested each setting on the lab site:

[30-Oct-2026 07:23:53 UTC] PHP Deprecated:  Creation of dynamic property MyPlugin::$items is deprecated in /var/www/html/wp-content/plugins/my-plugin/my-plugin.php on line 7

If you see this message, someone turned debugging on: you, a plugin that offers a debug mode, or a host's staging setup. Turning it off, or switching to the log, ends it.

When the message does real damage#

The message itself is harmless. Where it prints is not. Output that starts before WordPress sends its headers stops redirects from working. I put a four-line must-use plugin in wp-content/mu-plugins/early.php. It creates a property on an undeclared class in the admin_init hook, which runs before every admin screen:

<?phpclass EarlyThing {}add_action( 'admin_init', function () {	$t = new EarlyThing();	$t->cache = 1;} );

With display on, I saved Settings → General. The setting saved, but the page stayed on a block of text and never redirected. The screenshot below is the Dashboard, which shows the same text at the top:

The save returned 200 with this text in front of the page. With WP_DEBUG_DISPLAY off, the same save returned 302 to options-general.php?settings-updated=true. I re-ran both on the day of writing. The extra warnings are explained on the headers already sent page. Fix the first message and the rest go away.

Edge cases I tested#

• The attribute on old PHP. #[AllowDynamicProperties] ran without an error on PHP 7.4, because a line that starts with # is a comment there. Plugin authors can add it without raising their minimum PHP version.
• The attribute does not change behaviour. It only turns the message off. A class marked with it can still create typo properties.
• A global switch. Putting error_reporting( error_reporting() & ~E_DEPRECATED ); in a must-use plugin removed the message from the page on my test site. It hides every deprecation, including the ones that warn you about code that will stop working. Prefer the log.
• Not a reason to downgrade PHP. Going back to PHP 8.1 silences it, as the table above shows, but it only postpones the problem. Fix or replace the plugin instead.

If the page goes blank#

A deprecation never stops a page by itself. A blank page, or "There has been a critical error on this website", is a different problem: see the white screen of death and the critical error page.