I updated from Joomla 3.75 to 3.8. After that I could not access the backend. I got the error message: Error: 0 Call to undefined method JAdminCssMenu::addChild()
A menu is shown, but it does not work, you receive the same error messages.
The was an article in this forum with the error message:
Error: 0 Call to undefined method JAdminCssMenu::Load() or something like this. There was a tip to outcomment the following lines in /administrator/modules/mod_menu/mod_menu.php to receive back the control over the menu.
//$menu = new JAdminCssMenu;
But this does not work for me.
Can anybody please help?