Fatal error: Uncaught Error: Class 'WPMailSMTP\MigrationAbstract' not found in D:\www\wordpress - 安裝環境+外掛測試\02.外掛程式\常用外掛\wp-mail-smtp\src\Migration.php:17 Stack trace: #0 {main} thrown in D:\www\wordpress - 安裝環境+外掛測試\02.外掛程式\常用外掛\wp-mail-smtp\src\Migration.php on line 17