Fatal error: Uncaught Error: Class 'think\DbManager' not found in D:\php\WWW\xhqmzzwatdqc.cccf.net\vendor\topthink\framework\src\think\Db.php:20 Stack trace: #0 {main} thrown in D:\php\WWW\xhqmzzwatdqc.cccf.net\vendor\topthink\framework\src\think\Db.php on line 20