CodeIgniter Dynamic Property Deprecation Error in PHP 8.2

Problem Statement

When running CodeIgniter 3 applications on PHP 8.2+, you may encounter this error:

Severity: 8192
Message: Creation of dynamic property CI_URI::$config is deprecated
Filename: core/URI.php
Line Number: 102

This warning occurs in the CodeIgniter core files, typically in classes like:

• CI_URI
• CI_Router
• CI_Loader
• CI_Controller
• CI_DB_driver

The key issue is that PHP 8.2 introduced a deprecation warning for dynamic property creation - when classes reference properties that haven't been declared in the class definition.

Why This Happens

CodeIgniter 3 relies heavily on dynamic properties where class properties are created at runtime without explicit declaration. PHP 8.2 deprecated this pattern:

// In CodeIgniter's CI_URI class:
$this->config =& $config;  // $config property not declared

This produces E_DEPRECATED warnings (error level 8192) that can fill your logs and disrupt application behavior.

Important

This is not a fatal error but should be addressed:

• Deprecation warnings indicate future PHP compatibility issues
• Log files can become bloated with repeated warnings
• May cause visual disruption in development environments

Recommended Solution: Add AllowDynamicProperties Attribute

The most maintainable solution is to add the #[\AllowDynamicProperties] attribute to affected CodeIgniter core classes:

Steps to Apply the Fix

1. Open these core files:

   • /system/core/URI.php
   • /system/core/Router.php
   • /system/core/Loader.php
   • /system/core/Controller.php
   • /system/database/DB_driver.php

2. Add the #[\AllowDynamicProperties] attribute immediately above each class declaration:

#[\AllowDynamicProperties]
class CI_URI {

#[\AllowDynamicProperties]
class CI_Router {

#[\AllowDynamicProperties]
class CI_Loader {

#[\AllowDynamicProperties]
class CI_Controller {

#[\AllowDynamicProperties]
abstract class CI_DB_driver {

Why This Works

• The #[\AllowDynamicProperties] attribute tells PHP to allow dynamic property creation
• Minimal code change with maximum compatibility
• Preserves original framework behavior
• Officially recommended by the CodeIgniter community

TIP

After making these changes, clear your browser cache and restart your web server to ensure the changes take effect.

Alternative Solution: Declare Missing Properties

For specific classes triggering warnings, explicitly declare the missing properties:

class CI_URI {
    /**
     * Reference to the configuration object
     * @var CI_Config
     */
    public $config;

    // ... rest of the class ...
}

When to Use This Approach

• Only for one-off fixes in custom classes
• When you need to quickly resolve a single deprecation warning
• When modifying vendor files temporarily

Limitations

This approach becomes impractical when:

• Dealing with multiple affected classes
• Runtime creates different properties dynamically
• The needed properties aren't easily identifiable

Solutions to Avoid

❌ Suppressing Errors with @ Operator

// Don't do this!
$object = @new CI_URI();

• Masks the underlying problem
• May hide other important warnings
• Considered bad practice

❌ Disabling Deprecation Warnings

; In php.ini - not recommended
error_reporting = E_ALL & ~E_DEPRECATED

<?php
// In code - not recommended
ini_set('error_reporting', E_ALL & ~E_DEPRECATED);

• Suppresses valuable diagnostic information
• Will become ineffective in future PHP versions
• May hide other legitimate issues

Ultimate Solution: Upgrade to CodeIgniter 4

CodeIgniter 4 has full PHP 8.2+ support without deprecation issues:

composer create-project codeigniter4/appstarter

Migration Benefits

• Official PHP 8.2+ compatibility
• Modern framework architecture
• Continued maintenance and security updates
• Similar syntax with added features

Conclusion

For PHP 8.2 and later, add #[\AllowDynamicProperties] to CodeIgniter 3 core classes as shown to resolve dynamic property deprecation warnings:

1. Locate affected classes in /system/core/ and /system/database/
2. Add #[\AllowDynamicProperties] above each class declaration
3. Save changes and restart services
4. Verify warnings have disappeared

This fix maintains application functionality while preserving important deprecation warnings for other parts of your codebase. For long-term stability, plan migration to CodeIgniter 4.

Note

Always make core file changes in a controlled environment and maintain backups before modifying framework files.