Fatal error: Uncaught Error: Class 'Composer\Installer\LibraryInstaller' not found in D:\www\wordpress - 安裝環境+外掛測試\02.外掛程式\會員外掛\user-registration-pro\vendor\composer\installers\src\Composer\Installers\Installer.php:15 Stack trace: #0 {main} thrown in D:\www\wordpress - 安裝環境+外掛測試\02.外掛程式\會員外掛\user-registration-pro\vendor\composer\installers\src\Composer\Installers\Installer.php on line 15