A page template with the ID "" does not exist!

#0  Helpers::debugStringBacktrace() called at [/kunden/79567_33617/system/core/library/Helpers.php:44]
#1  Helpers::fatalError(A page template with the ID "" does not exist!) called at [/kunden/79567_33617/system/core/library/StandardPageBuilder.php:218]
#2  StandardPageBuilder->getPage(20, de) called at [/kunden/79567_33617/system/core/library/StandardFrontendController.php:90]
#3  StandardFrontendController->run() called at [/kunden/79567_33617/system/core/frontend/index.php:53]
#4  require_once(/kunden/79567_33617/system/core/frontend/index.php) called at [/kunden/79567_33617/index.php:95]