I got a freshly installed OC 18.104.22.168 with Kiddos running (no other extension installed yet). When trying to go through checkout I get the following error message already in the first step (where I should be able to choose guest checkout or login):
Fatal error: 'Unknown "endif" tag in "BurnEngine/template/checkout/login.twig" at line 50.'
#0 system/library/template/Twig/Parser.php(100): Twig_Parser->subparse(NULL, false)
#1 system/library/template/Twig/Environment.php(619): Twig_Parser->parse(Object(Twig_TokenStream))
#2 system/library/template/Twig/Environment.php(671): Twig_Environment->parse(Object(Twig_TokenStream))
#3 system/library/template/Twig/Environment.php(396): Twig_Environment->compileSource('
There is vqmod that is changing the catalog/view/theme/BurnEngine/template/checkout/login.twig.
Unfortunately the vqmod relies only on the exact default theme template line number (it uses offsetting) and BurnEngine changes the code a bit and breaks this thin logic. We’ve tried to found out what exactly should be replaced but couldn’t. Can you try show the plugin developer the new template – he should be able to help you better.