J3.x:Call to undefined method JAdminCssMenu::addChild in backend

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In Joomla! 3.8, the administrator menu module was updated to include new features. As a result of the changes, some extensions may have been broken by the 3.8 update.

Errors reported

Call to undefined method JAdminCssMenu::addChild

Versions affected

General Information

This pertains only to Joomla! version(s): 3.8.0

What is the cause

Changes in the administrator menu module to support new features.

How to fix

Ensure all extensions are updated prior to updating Joomla.