Slim Application Error

The application could not run because of the following error:

Details

Type: Twig_Error_Syntax
Message: A template that extends another one cannot include content outside Twig blocks. Did you forget to put the content inside a {% block %} tag?
File: /var/www/vhosts/alexander-n.com/httpdocs/src/templates/complex_htmlsitemap.twig
Line: 2

Trace

#0 /var/www/vhosts/alexander-n.com/httpdocs/vendor/twig/twig/lib/Twig/Parser.php(361): Twig_Parser->filterBodyNodes()
#1 /var/www/vhosts/alexander-n.com/httpdocs/vendor/twig/twig/lib/Twig/Parser.php(83): Twig_Parser->filterBodyNodes()
#2 /var/www/vhosts/alexander-n.com/httpdocs/vendor/twig/twig/lib/Twig/Environment.php(533): Twig_Parser->parse()
#3 /var/www/vhosts/alexander-n.com/httpdocs/vendor/twig/twig/lib/Twig/Environment.php(565): Twig_Environment->parse()
#4 /var/www/vhosts/alexander-n.com/httpdocs/vendor/twig/twig/lib/Twig/Environment.php(368): Twig_Environment->compileSource()
#5 /var/www/vhosts/alexander-n.com/httpdocs/vendor/twig/twig/lib/Twig/Environment.php(289): Twig_Environment->loadTemplate()
#6 /var/www/vhosts/alexander-n.com/httpdocs/vendor/slim/twig-view/src/Twig.php(89): Twig_Environment->render()
#7 /var/www/vhosts/alexander-n.com/httpdocs/vendor/slim/twig-view/src/Twig.php(195): Slim\Views\Twig->fetch()
#8 /var/www/vhosts/alexander-n.com/httpdocs/src/classes/Controllers/HomeController.php(2933): Slim\Views\Twig->render()
#9 [internal function]: App\Controllers\HomeController->sitemap_complexes()
#10 /var/www/vhosts/alexander-n.com/httpdocs/vendor/php-di/invoker/src/Invoker.php(82): call_user_func_array()
#11 /var/www/vhosts/alexander-n.com/httpdocs/vendor/php-di/slim-bridge/src/ControllerInvoker.php(50): Invoker\Invoker->call()
#12 /var/www/vhosts/alexander-n.com/httpdocs/vendor/slim/slim/Slim/Route.php(335): DI\Bridge\Slim\ControllerInvoker->__invoke()
#13 /var/www/vhosts/alexander-n.com/httpdocs/vendor/slim/slim/Slim/MiddlewareAwareTrait.php(117): Slim\Route->__invoke()
#14 /var/www/vhosts/alexander-n.com/httpdocs/vendor/slim/slim/Slim/Route.php(313): Slim\Route->callMiddlewareStack()
#15 /var/www/vhosts/alexander-n.com/httpdocs/vendor/slim/slim/Slim/App.php(513): Slim\Route->run()
#16 /var/www/vhosts/alexander-n.com/httpdocs/vendor/slim/slim/Slim/MiddlewareAwareTrait.php(117): Slim\App->__invoke()
#17 /var/www/vhosts/alexander-n.com/httpdocs/vendor/slim/slim/Slim/App.php(406): Slim\App->callMiddlewareStack()
#18 /var/www/vhosts/alexander-n.com/httpdocs/vendor/slim/slim/Slim/App.php(314): Slim\App->process()
#19 /var/www/vhosts/alexander-n.com/httpdocs/public/index.php(42): Slim\App->run()
#20 {main}