How do I replace JRule on Joomla 4 or 6?

JRule is a Joomla 3 global class. Joomla 4 still has an alias. Joomla 5 needs the Behaviour – Backward Compatibility plugin. Native Joomla 6 does not load that alias — you get Class "JRule" not found. Use Joomla\CMS\Access\Rule. Add a use statement for Joomla\CMS\Access\Rule. Replace every JRule with the short class name from that use line. Disable Behaviour – Backward Compatibility on a Joomla 5 staging site. If it fatals, this class is still in the code.

What error does JRule throw after a Joomla upgrade?

Class "JRule" not found. Class 'JRule' not found. Failed to open stream: JRule

Why does JRule class name break after migrating from Joomla 3?

JRule is a Joomla 3 global class. Joomla 4 still has an alias. Joomla 5 needs the Behaviour – Backward Compatibility plugin. Native Joomla 6 does not load that alias — you get Class "JRule" not found. People notice: white screen after disabling compatibility plugin, class not found on Joomla 6, works on Joomla 5 until I turn off backward compatibility.

JRULE-CLASS-001

JRule

JRule class name

JRule is a Joomla 3 global class. Joomla 4 still has an alias. Joomla 5 needs the Behaviour – Backward Compatibility plugin. Native Joomla 6 does not load that alias — you get Class "JRule" not found.

JRule → Joomla\CMS\Access\Rule

Dies at Joomla 5 → 6J3: Works nativelyJ4: Alias (old name still resolves)J6: Removed — fatalBC plugin: covers the class nameMechanical renameJoomla API

What you will see

Class "JRule" not found
Class 'JRule' not found
Failed to open stream: JRule

Symptoms people search

white screen after disabling compatibility plugin · class not found on Joomla 6 · works on Joomla 5 until I turn off backward compatibility

Replace this code

Swap JRule for Joomla\CMS\Access\Rule.

Joomla 3

Remove or stop calling this

JRule::getInstance();
// or new JRule()

Joomla 4 / 6

Use this instead

use Joomla\CMS\Access\Rule;

// Call the namespaced class. Do not keep the J prefix.

How to fix it

1Add a use statement for Joomla\CMS\Access\Rule.
2Replace every JRule with the short class name from that use line.
3Disable Behaviour – Backward Compatibility on a Joomla 5 staging site. If it fatals, this class is still in the code.

Also known as

JRule · Joomla\CMS\Access\Rule · class alias · J prefix · JAccessRule

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JRule

What you will see

Symptoms people search

Replace this code

How to fix it

Also known as

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