Reason for ‘Deprecated: Creation of dynamic property’ – Understanding and Dealing with PHP 8.2 x WordPress

When running a WordPress site on PHP 8.2, you may see the following warning in your logs or on the screen.

Deprecated: Creation of dynamic property … is deprecated

This is not a "site broken" error, but a warning about future compatibility. However, seeing it for the first time in large quantities can be unsettling, and in environments where WP_DEBUG is ON, it can interfere with site display.

In this article, I will clearly organize what is happening, why it appears, and how to deal with it.

1. What does this Deprecated warning mean?

From PHP 8.2, the creation of dynamic properties has been deprecated. A dynamic property is a property that is not included in the class definition but is added at runtime after the object is created.

For example, code like this will trigger a warning:

class Foo {}
$foo = new Foo;
$foo->bar = 1; // dynamic property

When executed, PHP 8.2 will issue a Deprecated: Creation of dynamic property warning. This is because a property that the class did not define in advance was added later.

2. Why did this warning start appearing?

Previous versions of PHP were designed to allow the free creation of dynamic properties, but in PHP 8.2, this has become Deprecated, and there is a possibility it will become an error in the future.

Therefore, if WordPress core, plugins, or theme code sets properties that do not exist in the class, PHP will now issue a warning.

3. Common Cases in WordPress

This warning does not affect actual operation, but it will be displayed in environments where WP_DEBUG is ON. If it appears in large quantities, it can make logs difficult to read or hinder error handling.

Common examples:

• Plugins maintaining internal state with dynamic properties
• Themes using dynamic properties
• WP core or subsystems using dynamic properties in some parts

These are codes that have not caught up with the specification changes in PHP 8.2.

4. What you should do right now

🔹 1. Update Plugins/Themes

If the source of the warning is a plugin or theme, it is often fixed in an update. First, update to the latest version.

🔹 2. Suppress WP_DEBUG display (Production Environment)

If the warning display is unsightly in a production environment, first set the following:

define('WP_DEBUG_DISPLAY', false);
define('WP_DEBUG_LOG', true);

This stops the display on the screen while keeping it in the log.

🔹 3. Code-side response (For Developers)

1. Declare properties in the class

class MyClass {
    public $myProp; // Declaration
}

2. Add the #[AllowDynamicProperties] attribute

In PHP 8.2, you can suppress the deprecated warning by specifying the following, but there is a possibility it will be removed in future specification changes.

#[AllowDynamicProperties]
class MyClass {}

5. Why did PHP 8.2 deprecate dynamic properties?

Dynamic properties are very flexible, but on the other hand, they have disadvantages:

• Unexpected properties get mixed in
• IDE completion does not work
• Easy to become a breeding ground for bugs

PHP is moving in the direction of stopping this, and the WP community is also proceeding with support.

6. Summary

• Deprecated: Creation of dynamic property is a warning, not a fatal error
• It started appearing due to specification changes from PHP 8.2
• Solutions are Plugin Update / Theme Fix / Display Suppression
• It is important to organize code for future PHP versions

This warning accompanies the maturity of PHP and WordPress. Instead of just thinking "I hate that I can't erase it," treating it as a signal to clean up the code will increase the long-term stability of the site.