Trying to load __session_manager via ClassAutoload::loader()

Fatal error: Uncaught Error: Using $this when not in object context in /homepages/18/d98778038/htdocs/---multidomain-network-v5.7/--global-core/--global-classes/--template-engine/__template_manager.system.php:22 Stack trace: #0 /homepages/18/d98778038/htdocs/---multidomain-network-v5.7/--global-core/index.php(69): __template_manager::checkTemplateDatabase() #1 {main} thrown in /homepages/18/d98778038/htdocs/---multidomain-network-v5.7/--global-core/--global-classes/--template-engine/__template_manager.system.php on line 22