An unhandled error occured

Extension file '.extension.php' does not exist!

Stack trace
#0 /customers/d/8/e/enslevforsamlingshus.dk/httpd.www/base/SMController.class.php(199): SMImageMontage->Render()
#1 /customers/d/8/e/enslevforsamlingshus.dk/httpd.www/base/SMController.class.php(139): SMController->loadExtension('SMImageMontage')
#2 /customers/d/8/e/enslevforsamlingshus.dk/httpd.www/index.php(22): SMController->Execute()
#3 {main}