In this page, https://holt59.github.io/cakephp3-bootstrap-helpers/panel-helper/basics/ you explain how to load the panel helper with:
public $helpers = [ 'Panel' => [ 'className' => 'Bootstrap.PanelHelper' ] ];
The little mistake is that it should be:
public $helpers = [ 'Panel' => [ 'className' => 'Bootstrap.Panel' ] ];
In this page, https://holt59.github.io/cakephp3-bootstrap-helpers/panel-helper/basics/ you explain how to load the panel helper with:
public $helpers = [ 'Panel' => [ 'className' => 'Bootstrap.PanelHelper' ] ];
The little mistake is that it should be:public $helpers = [ 'Panel' => [ 'className' => 'Bootstrap.Panel' ] ];